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Keywords:

  • climatic limitation;
  • communities;
  • conservation;
  • ecophysiology;
  • geographical and altitudinal distribution;
  • germination;
  • herbivory;
  • mycorrhiza;
  • parasites and diseases;
  • reproductive biology;
  • soils

Summary

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

1. This account presents information on all aspects of the biology of Cirsium arvense that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, conservation and management.

2.Cirsium arvense, creeping thistle (Californian thistle, Canada thistle), one of the world’s most troublesome and persistent weeds, is native to Europe and the east northern hemisphere but introduced to North America and the southern hemisphere. Latitudinal distribution north or south is limited by low winter and summer maximum temperatures and by a long day requirement for flowering.

3.Cirsium arvense is believed to have originated in the temperate Middle East and its spread has closely followed human migration and agricultural activity. Colonization of new sites is by seed which establishes best in bare or disturbed ground, mirroring its prehistoric ecology as an opportunist pioneer of bare ground and organic residues. It is now a widespread and scheduled agricultural weed in both arable crops and pastures and also a constituent in over 70 British (National Vegetation Classification) plant communities, occurring mainly on waste neglected land, roadsides, hedgerows and disturbed areas.

4. Its presence in crops leads to yield losses and in pastures seriously interferes with utilization due to the deterrent effect of the leaf spines on grazing animals. This has led to a long history of investigation into control measures: mechanical, chemical, biological and integrated, which are summarized. Combination treatments and integrated control have achieved some success but effective control requires follow-up procedures over a number of seasons. Climate change studies suggest C. arvense could grow better and be more difficult to control in future.

5. Success and persistence derives from an extensive, far-creeping and deep rooting system which ensures survival and rapid vegetative spread under a wide range of soil and management conditions, and a means of escape from sub-aerial control treatments. New adventitious buds capable of shoot development can arise at any point along the horizontal roots, even when these are cut into pieces or damaged. Root buds remain dormant until released from dormancy through damage or decay of the aerial shoots. Carbohydrate root reserves, stored in swollen cortical tissue, fall to a minimum just before flowering and are then replenished for perennation during the subsequent winter. Strategies for control aim to treat the plant when root carbohydrate reserves are at a minimum, to exhaust these reserves and to prevent replenishment for further perennation.

6. Balanced against its difficulty as a weed, C. arvense has significant conservation value as a host to numerous insects, many attracted by copious and accessible nectar and strong flower fragrance. It is however a strong competitor to low-growing plants in natural communities.

7.Cirsium arvense is dioecious and for flowering has a 14–16 h day length requirement. Seed set is successful if male and female plants are no more than 50–90 m apart to allow insect pollination. In spite of the conspicuous wind-borne pappus, this rarely carries a seed which normally falls near the parent plant. The flower heads and other plant parts are regularly attacked by numerous insects and less frequently by diseases.

8. Germination of seed is mainly during the high temperatures of early summer in the year following dispersal and establishment is most successful in open areas. Development of the branching root system and vegetative spread follow rapidly.

9. A combination of dioecy and vegetative reproduction has resulted in the maintenance of genotypic and genetic diversities within populations allowing efficient colonization and persistence, contributing greatly to success in the species.

Asteraceae, tribe Cardueae, Cirsium Section Cephalonophos DC. Cirsium arvense (L.) Scop. (Creeping thistle, California thistle, Canada thistle). Erect polycarpic perennial herb initially with a slender tap root producing far-creeping white or yellowish rhizome-like roots. Horizontal roots > 5 m long, vertical roots 2–5 m deep, with an extensive system of absorbing roots, bearing numerous adventitious non-flowering and flowering shoots. Stems erect, 30–150 (180) cm, pale yellowish green, sometimes tinted or suffused brownish-purple, channelled and ridged, usually paniculately much-branched, leafy to apex, not winged, nearly glabrous or slightly hairy when young, increasingly hairy with age. Roots and young stems with sparse latex vessels. Leaves 10–20 × 2–5 cm, dull medium-yellowish to dark green with pale midrib, paler beneath, rarely whitish, alternate, oblong or lanceolate with attenuate bases, lower short-stalked, upper leaves sessile to semi-amplexicaul, slightly decurrent with a narrow base continuing down the stem, giving the appearance of a spiny stem; leaves entire to pinnatifid, edges crinkled, sub-denticulate, with frequent short (1–10 mm) strong spines and terminating in a spine; very irregularly lobed with broad to narrow triangular segments, rounded-acute, spinose-dentate and undulate, such that the spines are multiplanar, orientated in all directions; surface glabrous or sparsely arachnoid-hairy above, without rigid setae, glabrous to arachnoid-tomentose beneath.

Plants incompletely dioecious, capitula shortly pedunculate in terminal and axillary corymb-like clusters, solitary or two to three per cluster, 1.5–2.5 cm × 0.8–2 cm (excluding flowers), peduncles short, yellowish green or purplish. Heads discoid, involucre (9) 12–17 (20) × (6) 8–12 (15) mm, glabrous or somewhat cottony, bracts or phyllaries numerous appressed, subulate, overlapping, with distinct vittae, pale green but often suffused purplish; outer obtuse, ovate or ovato-lanceolate, tipped with short ± spreading prickly points; middle acute; inner bracts of pistillate heads linear elongated; innermost unarmed with erect scarious tips (Moore & Frankton 1974). Staminate heads oblong globose, with corollas projecting; pistillate heads ovoid or flask-shaped, campanulate, corollas shorter. Florets unisexual, corolla (10) 13–18 mm, pink or pale purple, occasionally white, limb 5-cleft regularly almost to base, less than half as long as tube, strongly honey-scented. Receptacle flat, deeply pitted, bristly, chaffy. Achenes oblong, smooth, shiny, finely grooved lengthwise, curved or straight, ± 4-angled, flattened at the apex with a characteristic conical point in the centre, 2.5–4 mm long, light to dark brown, surmounted by a conspicuous pappus (5) 20–30 mm long and, in female flowers, much longer than the corolla when mature. Pappus, grey white to brownish, made up of c. 70 (Lund & Rostrup 1901) proximally united rays, bearing numerous plumose hairs 2–3 mm long, readily separating from the achene (deciduous), leaving a small projection at its apex.

Specimen 965.19 in the Linnaean Herbarium, London is the lectotype of Serratula arvensis L., the basionym of Cirsium arvense (L.) Scop, which was probably described from cultivated fields in Europe (Moore & Frankton 1974; Jarvis 2007). Wimmer & Grabowski (1829 citied by thind 1975) originally described 4 varieties: horridum, mite, integrifulinm and vestitum, on the basis of spininess. Five varieties occur in Great Britain and Ireland (Sell & Murrell 2006):

  • 1
     var. maritimum Fr. In coastal habitats of dune and shingle.
  • 2
     var. arvense. The common form as a weed in fields, waste places and grassland.
  • 3
     var. horridum Wimm. & Grab. Scattered localities mainly near the sea; Continental Europe; common in north America (Moore & Frankton 1974).
  • 4
     var. integrifolium Wimm. & Grab. (var. setosum (Willd.) C.A. Mey; var. mite Wimm. & Grab.). Introduced casual; native to Central Europe and Southeast Asia.
  • 5
     var. vestitum Wimm. & Grab. (var. incanum (S. G. Gmel.) Ledeb.). Introduced casual in S. England (Stace 1997), recorded from Ross, W. Hereford; native in S. Europe and W. Asia.

The brief descriptions of their chief characters given by Sell & Murrell (2006) are summarized in Table 1 and typical leaf shapes are shown in Fig. 1. Hultén & Fries (1986) recognized vars integrifolium and vestitum as subspecies.Tutin et al. (1976) considered infra-specific taxa or specific taxa are best treated as varieties, since there are gradual transitions of characteristics, e.g. of leaves, leaf segments and indumentum, and there is no evidence of ecogeographic differences between them. Moore & Frankton (1974) also considered that, as the variants could interbreed, these did not merit the specific rank suggested by Charadze (1963). A form with white flowers, forma albiflorum (Rand. & Redf.) R, Hoffm. and one with a red pigmented involucre, forma rubricaule Lepage, occurring in Canada, were mentioned by Moore & Frankton (1974).

Table 1.   Varietal characteristics in Cirsium arvense (from Sell & Murrell 2006)
CharacterVariety
maritimumarvensehorridumintegrifoliumvestitum
StemsSolitaryOften > 1Often > 1Often > 1Often > 1
Maximum height (cm)50150150150150
Leaf under surfaceGreenGreenGreenOccasionally arachnoid-hairyWhite or grey tomentose
LeavesDeeply lobedDeeply obtuse lobedDeeply acute lobedSub-entire to undulate lobedSub-entire to shallow undulate lobed
LaminaThree-dimensionalThree-dimensionalThree-dimensionalFlatFlat
Width of undivided area near leaf midrib (mm)101503535
Leaf spinesStrongly spinoseStrongly spinoseLobes strongly spine-tippedMargins weakly spine-tippedMargins weakly spine-tipped
CapitulaFewManyManyManyMany
InflorescenceUnbranched condensedBranched openBranched openBranched openBranched
image

Figure 1.  Silhouetted leaf shapes of Cirsium arvense varieties, mid-stem. (a) var. maritimum; (b) var. arvense; (c) var. horridum; (d) var. integrifolium; (e) var. vestitum.(from photocopies supplied by P.D. Sell & J. Gina Murrell, University Herbarium, Plant Sciences Department, University of Cambridge, with acknowledgement).

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Consequent upon its outbreeding, there is great variation among plants derived from seed. However, these morphological differences arise not only from genetic traits but also vary with different habitats and are not constant (Detmers 1927). Using molecular techniques (AFLP) Soléet al. (2004) established that genotypic and genetic diversities did not decline with time in C. arvense populations but were maintained at a high level within and between populations. This was attributed to a combination of recruitment of sexually outcrossed seedlings in the early stages of succession with clonal reproduction, resulting in efficient colonization and local persistence thus contributing to success of the species worldwide. High values for genetic diversity were found by Hettwer & Steinmann (2002), using similar techniques, confirming that sexual reproduction was important. Hodgson (1964) collected different clones, which he termed ecotypes, from separate geographical areas; these showed structural, growth and physiological differences. Differential photoperiodic response and root and shoot development among seven ecotypes were also recorded by Hunter & Smith (1972).

Native. C. arvense is one of the world’s most troublesome and persistent weeds, native to Europe and temperate Asia, but introduced to North America and the southern hemisphere. It is a common and abundant weed of cultivated land and pastures, waysides, hedgerows, waste and neglected places. With a perennial creeping and extensively branched root system, it is a noxious weed that is difficult to control and leads to serious economic losses.

I. Geographical and altitudinal distribution

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

In the British Isles C. arvense is recorded from almost every vice-county and 96% (2750) of 10-km squares in Britain and 96% (968) in Ireland (Fig. 2). It is absent from the highest mountains in Scotland, England and Wales. The mean altitude of non-coastal squares in Britain is 172 m and of non-coastal squares without a record, 439 m. Its absence from the highest ground in Cumbria is clearly shown by maps at the tetrad scale (Halliday 1997). Cirsium arvense is native to the old world of the northern hemisphere: all of Europe, N. Africa, Asia Minor, Afghanistan, Siberia, China and Japan (Holm et al. 1977; Kasahara 1982; Weber 2005). Its native distribution is classified as Temperate Eurasian by Preston & Hill (1997) but it now has a Temperate Circumpolar range. It is present throughout Europe (Fig. 3) except in the Azores, Crete and Svalbard and is not native in the Faroe Islands (Holm et al. 1977; Hultén & Fries 1986). Reviews in Holzner & Numata (1982) indicate it is common in: cereals, vineyards and fallow land in France and Spain (Guillerm & Maillet 1982), the heavier soils of north and south Italy (Franzini 1982) and low value pastures in the European Alps (Dietl 1982). Its presence is recorded on crop land in Croatia (Purgar & Hulina 2008), Serbia (Vrbnicanin et al. 2008), Slovakia (Macak et al. 2008), Hungary (Nemeth 2001) and Belarus (Privalov, Soroka & Sorochinskii 2008) and on non-cropped land in Poland (Korniak & Kalwasinska 2001), Serbia (Pavlovic, Mitrovic & Djurdjevic 2004), Bulgaria (Dimitrova & Marinov-Serafimov 2008) and the Czech Republic (Gaisler, Pavlu & Hejeman 2008).

image

Figure 2.  The distribution of Cirsium arvense in the British Isles. Each dot represents at least one record in a 10-km square of the National Grid. (inline image) native 1970 onwards; (inline image) native pre-1970. Mapped by Stephanie Ames, Biological Records Centre, Centre for Ecology and Hydrology, mainly from records collected by members of the Botanical Society of the British Isles, using Dr A. Morton’s DMAP software.

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image

Figure 3.  Distribution of Cirsium arvense in the northern hemisphere. Reproduced from Hultén and Fries (1986) Atlas of North European Plants North of the Tropic of Cancer, Volume II, with permission of Koeltz Scientific Books, Koenigstein, Germany. Key: inline image: isolated, fairly exact indicated occurrences; ////: common or fairly common occurrence within the area; inline image: incompletely or approximately stated occurrences.

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As it is principally a species of agricultural areas, the geographical and altitudinal distributions follow the sphere of agricultural influence. In the northern hemisphere it is found to 68°N in Siberia, at 37°N in USA, at 30°N in N. Africa. In Russia it thrives to 58°N but does not flower at 58–59°N (Moore 1975). It is present in Russian montane forests (Vishnyakov 1979) and in the river valleys and northern exposed slopes of Mongolia (Hilbig 1982). It is now a serious agricultural weed in all Canadian provinces, with a wide distribution and high frequency throughout the cereal lands of western Canada (Alex 1966, quoted by Moore 1975). It is abundant in the USA north of latitude c. 37°N, in the eastern states to 97°W and in the Pacific states, but does not survive in the more southerly states. Creeping thistle is recorded as a common weed of arable crops in the Indian subcontinent (Gupta & Murty 1986; Khan & William 1989), and in Turkey (Mennan & Isik 2003).

In the southern hemisphere it has been introduced into S. America and S. Africa, occurring northwards to 25°S in the Transvaal (Holm et al. 1977). Following similar introduction, it is now a serious weed in Australia and New Zealand, both North and South Islands (Rahman 1982). On the Australian mainland it occurs mainly in the south east (Briese 1988), a localized infestation in Western Australia having been controlled (Meadly 1957).

II. Habitat

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

(A) Climatic and topographical limitations

Cirsium arvense is most common at lower altitudes with a distribution centred on temperate zones with moderate summer temperatures. It does not survive in equatorial regions even in high altitude areas, e.g. East Africa. There was a widespread distribution in almost every municipal unit of Canada in the survey by Alex (1966), covering between 5% and 67% of agricultural land. The northern limit of greater abundance corresponded to the −18 °C January isotherm, though −27 to −35 °C winter minima were common within the range of the weed. However, under snow cover there would be higher soil temperatures. Annual rainfall varied widely from 300 to 1000 mm. In Victoria, Australia, it occurs under 700–1000 mm annual rainfall and at latitudes > 13°S (Amor & Harris 1974). Southern limits in the northern hemisphere are probably limited by the unsuitable high summer temperatures in combination with the long-day requirement for flowering. It is possible that the root storage physiology is disrupted by the constantly elevated soil temperatures, since the ability of C3 plants to produce underground roots is impaired at tropical temperatures (Håkansson 2003). Low winter temperatures and short growing seasons probably determine northern limits. In UK records occur to 700 m in the Breadalbanes and to 845 m on Great Dun Fell, Cumbria (Pearman & Corner 2004), with winter soil temperatures, soil acidity and inhospitable terrain the main limiting factors at higher altitudes. No latitudinal trends in population density, seed production or morphological traits were detected in UK thistle populations by Jump & Woodward (2003).

(B) Substratum

Cirsium arvense occurs on a wide range of soil types. A deep-rooting habit leads to intolerance of permanent waterlogging and there is a preference for nutrient-rich substrata or those with accumulated organic residues. It was traditionally thought to be an indicator of good land (Murray et al. 1919; Fairbairn & Thomas 1959) and is particularly associated with fertile soils, manure heaps and garden soils; growth is stimulated by fertilizers. It does not occur on very acid soils and thrives best on circum-neutral soils. Grime & Lloyd (1973) found that thistle seedlings in the Peak District occurred more often when the surface pH was above 4.0 and were absent from the acidic Millstone Grit and Bunter sandstones. It has established as an occasional on reinstated upland peat (G. Tiley, unpubl. data) and became abundant when 75% highly acidic pyritic peat was mixed with arable soil in lowland conditions (Dunsford, Free & Davy 1998). It occurs widely on the UK chalk where it is capable of colonizing the bare rock (Locket 1946) and is reported to last longer on soils with chalk in Germany (Moore 1975). Medium-textured, well-aerated loams are best to maintain optimum moisture for root growth. In Denmark, Lund & Rostrup (1901) recorded better growth in clay soils than in peat or on chalk; in sand growth was poor. Root extension followed a similar pattern. Where there were contrasting soil types within a profile, root growth was more extensive in the more favourable soil; e.g. in clay beneath sand or in peat above sand or chalk. In USA where summer temperatures are higher than in UK, root extension growth was found to be highest in clay (4.5 m), compared with 3.75 m in organic soil, 1.75 m in limestone and 1.0 m in sand (Detmers 1927). Rapid vegetative spread was possible on the Netherlands polders after drainage (Bakker 1960). Dark brown silt was also found to be favourable (Hodgson 1968). In Victoria, Australia, Amor & Harris (1974) stated that friable red loam with clay subsoils, pH 5–5.5, were best. In Canada it occurs on sand dunes, as in UK, and on sandy clay (Moore 1975). A UK National survey of permanent pasture (Peel & Hopkins 1980) indicated a greater frequency of thistle where K concentrations were relatively high (index 2–3) but P concentrations were lower (index 0 or 1), and a reduced frequency on soils with impeded drainage. Tolerance of salinity is indicated by the presence in coastal and maritime communities. Occurrence in the USA was noted on soils containing up to 2% salt (Reed & Hughes 1970). While a moderate instability of substrate is tolerated naturally as in some sand dune communities or under artificial cultivation, effects on moisture availability could be critical during dry periods.

III. Communities

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

Cirsium arvense is widespread throughout the UK, present primarily on or near land under human influence but also as a constituent of natural communities, most often where there is disturbance, open vegetation or reduced management. It generally occurs in patches or clumps as a result of vegetative spread; infrequent or isolated plants are found in less favourable habitats. Rodwell (1991a,b, 1992, 1995, 2000) documents the presence of Cirsium arvense in 75 British plant communities, incorporating 148 sub-communities (see Table S1 in Supporting Information). These are most numerous in the mesotrophic grassland, sand dune and open habitat community types. It is not recorded from any heathland or aquatic communities nor in the majority of woodland, mire, acid grassland, swamp and maritime cliff communities. In the absence of permanent inundation or the development of deep shade, C. arvense is unlikely to die out or be suppressed where it is present in natural communities. The following synopsis is based on British plant community descriptions (Rodwell 1991a,b, 1992, 1995, 2000):

Grassland

By far the most extensive and economically important occurrences of Cirsium arvense are in the two mesophytic agricultural grassland communities: MG6, the Lolium perenne-Cynosurus cristatus grassland, and MG7, the Lolium perenne leys and related grasslands. MG 6 encompasses much grazed permanent pasture where creeping thistle presence varies from a few plants to large patches of a persistent and tenacious weed. It is less common under the regular cultivation of temporary leys (MG7) but here often seen at the edges of fields. It was estimated by Perrott (1987) to occupy over 1 million ha of grassland in UK. Cirsium arvense also figures prominently in MG1, the Arrhenatherum elatius grassland, common on roadsides and open spaces which are subject to regular and infrequent cutting but ungrazed, leading to a coarse, open and tussocky sward. It is a weedy component of several other mesotrophic grasslands, e.g. the MG11 Festuca rubra-Agrostis stolonifera-Potentilla anserina community.

Creeping thistle is an infrequent component of very dense calcicolous grasslands with low-growing vegetation and nutrient-poor soils. On the chalk downland CG2 Festuca ovina-Avenula pratensis community, it occurs as an occasional invasive particularly in nutrient-rich areas (Smith 1980). It occurred as a casual on the more open swards of CG3 Bromus erectus and CG6 Avenula pubescens grasslands of the Oolite, but not in closed swards on Carboniferous limestone (G. Tiley, unpubl. data). Cirsium arvense was not seen in traditional hay meadow vegetation, MG5 Cynosurus cristatus-Centaurea nigra grassland in Skye (Birks 1973; 2003 or in Yorkshire (Smith & Jones 1991). It is unrecorded on calcifugous grasslands, except on the better or improved soils following mis-management, in U4, the Festuca ovina-Agrostis capillaris-Galium saxatile community. Thinner and more grassy stands of U20 Pteridium aquilinum-Galium saxatile also support Cirsium arvense, especially after disturbance.

Sand dunes

Cirsium arvense is an occasional component of 13 sand dune communities though never in great abundance except in the SD9 Ammophila arenaria-Arrhenatherum elatius dune grassland and, to a lesser extent in SD1 Rumex crispus-Glaucium flavum shingle community, SD6 Ammophila arenaria mobile dune community, SD7 Ammophila arenaria-Festuca rubra community and the SD18 Hippophae rhamnoides dune scrub. In these communities the soil is relatively more stable and less drought-prone and C. arvense can be an early colonist, especially where there has been an accumulation of strandline or tidal organic detritus.

Open habitats

Greatest constancy and abundance of C. arvense among the 75 UK communities were reported for the OV25 Urtica dioica-Cirsium arvense community, occurring on disturbed nutrient-rich loam in badly managed pastures and leys, abandoned arable land, waysides, verges, woodland clearings and waste ground. It is also a common species in several other open herbaceous communities, e.g. the OV22 Poa annua-Taraxacum officinale community along tracks and road verges and the OV24 Urtica dioica-Galium aparine community on disturbed, nutrient-rich ground near soil dumps, manure heaps, rubbish and waste ground. It is a frequent constituent of weedy areas on arable land, such as the OV13 Stellaria media-Capsella bursa-pastoris community.

Swamps, saltmarsh and maritime cliff

There is a very scattered occurrence in eight swamp and tall herb communities and with very limited abundance. It is however locally frequent in S24 the Phragmites australis-Urtica dioica tall herb fen, in association with Arrhenatherum elatius on moist, disturbed nutrient-rich soil which can dry out for some of the year. Presence in the other swamp communities is often at the fringes with pastures. In the SM18 Juncus maritimus and SM28 Elymus repens saltmarsh communities, thistle occurrence is restricted to areas of accumulated organic litter, with disturbance and fresh water influence in the SM28 community. Cirsium arvense is of limited occurrence in the maritime MC4 Brassica oleraceus cliff-edge community and the MC8 Festuca rubra-Armeria maritima maritime grassland, both being affected by salt spray. It is more common in the open unstable habitat of MC4 than in the thickly growing Festuca rubra of MC8.

Woodland and scrub; mires and heaths

While the presence of C. arvense is precluded by shade in mature woodland, it is a component of three scrub communities found at the edges of woodland: W21 Crataegus monogyna-Hedera helix scrub, W24 Rubus fruticosus-Holcus lanatus under scrub and W25 Pteridium aquilinum-Rubus fruticosus under scrub. It is most prominent in the coarse, open vegetation of W24 and only of low constancy in the other two communities. Two fen meadow communities, M22 Juncus subnodulosus-Cirsium palustre and M24 Molinia caerulea-Cirsium dissectum, subject to mowing and grazing, support C. arvense in better drained areas. It is locally frequent with tall herbs in the M28 Iris pseudacorus-Filipendula ulmaria mire, and present in the M27 Filipendula ulmaria-Angelica sylvestris mire.

IV. Response to biotic factors

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

Grazing and trampling

Abundant spines on the leaves and shoots of Cirsium arvense normally deter the attention of grazing animals, with the exception of horses, donkeys (Stroh et al. 2002), goats (Harrington, Beskow & Hodgson 2008), bison (Fortin et al. 2003) and pigs (Håkansson 2003). Deer browse the senesced stems (Windels & Jordan 2008). Horses and sometimes cattle eat the cut stems, from the base upwards. The spines become less formidable when the leaves are flaccid and plants may be eaten when wilted after cutting, mechanically bruised by clod crusher (Van Toor 1995) or trampled by stock (Mitchell & Abernethy 1995). A trial to reduce thistles in upland pastures by goat grazing showed little effects after 2 years (Scottish Agricultural College, unpubl. data), possibly because alternative grass herbage was available. Harrington, Beskow & Hodgson (2008) found that heavily stocked goats (410 ha−1) grazed 97% of thistle in 3 days when a 20 cm surround of forage was cut around the thistle shoots but only 3% without cutting. This result suggested that goats could give better control where a pasture was grazed down first by other stock. Cattle and sheep occasionally browse thistle shoots when grazing becomes limited in the autumn. Otherwise a heavy grazing management tends to increase thistle growth by the removal of competition from neighbouring grass, whereas lighter grazing allows competition from the surrounding grass, which is selectively ignored by animals leading to more vigorous growth (Oswald 1985). This was also found on Anticosta Island, Canada where heavy grazing by white-tailed deer, Odocoileus viginianus (Zimmerman) led to an increase in thistle cover (Casabon & Pothier 2008).

Jones (1933b) found overgrazing in winter and early spring followed by undergrazing in summer led to deterioration of the sward due to weakening of the more palatable grasses and increases in weed grasses (Agrostis capillaris and Holcus lanatus) and creeping thistle. Palatable species were overgrazed in winter and selectively grazed in summer, allowing strengthening of thistle and other weeds. Thus Jones concluded that the selection of grass species to be sown and the type of management given were factors that could influence the control of thistles. Heavy grazing by cattle reduced the rate of spread of Cirsium arvense as measured by patch diameter (Amor & Harris 1975). Results from a large-scale trial replicated in central England and in Wales (Pywell 2006, 2010) showed a significant reduction in thistle shoot development in both upland and lowland pasture. The most effective combination was of lenient autumn grazing with either grass topping or weed wiper application of herbicide, continued for two consecutive seasons. In contrast, heavy autumn grazing and winter grazing by sheep significantly increased the spring emergence of thistle shoots. Cattle reduced shoot numbers more than sheep. Heavy spring grazing did not affect shoot density, although it was of benefit for subsequent weed wiping. It was concluded that long-term grazing strategies were required for continued suppression of creeping thistle. Radkowski & Barabasz-Krasny (2007) found that cut and fertilized plots of montane permanent grassland in Poland developed higher value swards than those left fallow and unused which degraded to a low feed value with a dominance of weeds including C. arvense. Pavlu et al. (2007) recorded similar results in an experiment on abandoned montane semi-natural grassland in the Czech Republic. Tall forbs including C. arvense that were most abundant in the unmanaged treatments declined progressively as intensity of grazing management increased.

Similar results were obtained from a Canadian study on Alberta pastures (De Bruijn & Bork 2006) where high-intensity, low-frequency grazing reduced thistle shoot density, biomass and flowering, resulting in better control than short-duration, high-frequency grazing. Two intense defoliations annually for 2–3 years nearly eliminated thistle infestation. Trampling by animals and from tractor wheeling may have some effects on the thistle if the stems are sufficiently damaged to cause death or disruption to normal growth. However, there is often a rapid multi-shoot recovery of thistle on heavily poached areas (Edwards, Bourdôt & Crawley 2000). In New Zealand a strategy of frequent (every 3–4 weeks), very intensive grazing by sheep after an initial ‘knockdown’ cut in early summer, allows the thistles to be grazed in a soft condition, leading to practical elimination after 2 years (Mitchell & Keoghan 2008).

Cutting

Cutting or topping is often incorporated into the cosmetic management of thistles in grassland, roadsides, orchards, etc. Many references report that repeated cutting can reduce shoot density. Damage or removal of the stem to interrupt the translocation of photosynthates for storage in the roots was recognized as important in many early accounts (Stevens 1847; Detmers 1927), and reference was made to ‘starving’ the roots (Hansen 1918). Timing and frequency of cuts can influence the effectiveness of control. A farming tradition in S. England states: ‘Cut (thistle) in May, they are back the next day; cut in June, they will come back soon; cut in July, they will die’. Hedworth-Foulkes (1909) reported on a trial cutting regularly grazed pasture in June and twice in July which practically cleared thistle after 3 years. The timing of cuts depended on the season but was aimed for a 10–15 cm stem height. Growth of the underground roots was reduced by checking stem growth in early summer, leading to progressively less vigorous growth. Welton, Morris & Hatzler (1929) found in Ohio that cutting monthly in June, July and August was more effective than cutting in July, August and September, and nearly eliminated the thistle if repeated for 3 years. Willard & Lewis (1934), recommended cutting on 1 June and then at 4–6 week intervals. The best time for cutting was considered to be shortly before the first flowers open, when food reserves in the roots are lowest (Haggar, Oswald & Richardson 1986; VI E). Bourdôt et al. (1998) showed that mowing in late autumn was more effective in reducing overwintering root biomass due to a greater effect on shoot biomass duration; autumn root biomass was linearly related to the aerial shoot biomass of the previous summer. Infrequent cutting is ineffective (Amor & Harris 1975) and experience suggests that cutting gives only a check and not complete control. In cereal crops, cutting is clearly not possible until harvest. An annual decrease in thistle density by regular cutting within a lucerne crop was found by Schreiber (1967) though the final data on persistence were not given. Lucerne is well adapted to regular cutting with its rapid regrowth providing competitive cover to the slower growing thistle.

Dense stands of thistle can be cut for hay at the flowering stage, with two to three repeat cuts followed by grazing and continued for 2–3 years. After 18 years of cutting roadside vegetation at different frequencies per annum, Parr & Way (1988) observed lower shoot densities at high cutting frequencies (2–5 cuts per year). The greatest reductions in shoot density occurred between 0–1 and 1–2 cuts annually. Removal of cuttings resulted in a lower shoot density compared with non-removal.

Cutting and mulching has been tried as a means of smothering thistle recovery and, when performed at least twice a year on an upland semi-natural meadow in the Czech Republic, restricted thistle growth. Cutting and mulching only once yearly with no management resulted in a thistle increase (Gaisler, Pavlu & Hejeman 2008). Comparing the effects on thistle emergence of four organic mulches (wheat straw, peat, sawdust and grass) at 5 and 10 cm thicknesses with unmulched treatment in Lithuania, Jodaugiene, Pupaliene & Sinkeviciene (2008) obtained variable results after 3 years, though shoot emergence was lower under grass. There were no significant differences between the two mulch thicknesses, but crop yields and soil shear strengths were negatively correlated with thistle shoot numbers.

Entry of rain water into the cut ends of mature stems has been considered to introduce decay and weakening of below-ground organs in addition to the removal of photosynthetic tissue (Stevens 1847; Simpson 1993). Based on the studies of Hunter, Hsiao & McIntyre (1985), Nuzzo (1997) recommended leaving at least nine leaves or 20 cm bare stem when mowing since these can inhibit the development of shoots from the root buds.

A cutting treatment is now included in integrated methods of control (Pywell 2006; Mitchell & Keoghan 2008). Cutting is also essential to prevent flowering or seeding and the potential for spread by seed dispersal. Hand pulling and burning are analogous to cutting as a means of stem removal, but hand pulling was not regarded as economically effective by Morishita (1998) due to limited effects on the root system as well as being highly labour-intensive.

Annual burning has been tried to control thistle in North American natural grasslands with mixed success (Nuzzo 1997), sometimes reducing flowering, seed production or shoot density, sometimes increasing biomass and density. Olson (1975), quoted by Evans (1984), found that burning cool season grassland in May and warm season grassland in June gave an immediate reduction in thistle, though burning warm season grassland earlier produced short-term increases. In Manitoba marsh communities, summer burns produced an open vegetation in which thistle seedlings established, whereas spring-burnt vegetation remained unchanged (Thompson & Shay 1988). Travnicek, Lym & Prosser (2005) found that prescribed fall burns initially increased thistle densities due to lack of competition from indigenous species. In nature conservation areas wide-scale control treatments such as mechanized cutting, intensive grazing or mid-season burning are undesirable due to potential damage to the natural vegetation, especially in high value sites. Reviews of the control options available for natural areas have been made by Evans (1984), Simpson (1993), Nuzzo (1997) and Bond, Davies & Turner (2006).

Cultivations

Early farmers were aware of the effects of cultivation on creeping thistle, both in the dispersal of the roots and also for possible control by disturbing the soil. Stevens (1847) reported that frequent ploughing could control shallow rooting thistle. As with cutting the aim was to starve the roots and to prevent further shoot emergence and assimilate production (Hodgson 1968). Primary cultivations available are ploughing or discing; secondary cultivations are harrowing, sweep (duckfoot) cultivation or hand hoeing. Type of cultivator, depth of working, time of first cultivation, frequency and duration, and integration into the cropping system are all factors in the choice of cultivation treatment. Timing of the initial operation is important. Detmers (1927) and Hodgson (1968) recommended an early start to summer fallow cultivations. Weekly or fortnightly cultivations beginning after 2.5 cm of shoot growth resulted in complete control whereas delaying the start until flowering in mid-August was ineffective (Donald 1990). Cutting below the soil surface is easier than at deeper levels and with less risk of dispersing the roots and is the best mechanical control method for cultivated row crops. The duckfoot sweep cultivation was successful since it undercut the shoots (Donald 1990). In Sweden local infestations were sometimes controlled using a sharp-edged ‘thistle iron’ (Håkansson 2003). Treatment needs to continue throughout the season involving considerable inputs. Seely (1952, cited by Alley 1981) found that cultivating every 28 days required the least number of cultivations to achieve eradication and maximum depletion of root reserves at the end of the season. Follow-up treatment in subsequent years is important, by continuing clean cultivation, summer fallowing or use of a smother crop.

Fallowing (cultivating land without cropping) has also been widely used to reduce thistle populations in arable ground. Repeated for 2–3 years, fallowing eliminated thistle in arid U.S. western states. Cultivation every 21 days for one season eliminated 99% of thistle. Combining this with alternate years of wheat crops treated with 2,4-D led to almost complete elimination in 4 years (Hodgson 1958). Regular tillage treatment involving ploughing or cultivation in alternate weeks for 2 years was effective in control (Tingey 1934, cited by Donald 1990). The objective of summer fallow cultivations is to prevent shoot growth, and frequencies should be timed so that growth is no more than 7.5 cm. Optimum frequency, depth and type of cultivation depend on local and seasonal growing conditions. A higher frequency was required earlier in the season when the rate of re-emergence was greater; six to eight cultivations through the season adequately controlled regrowth. This was costly with a risk of soil erosion from wind and water and other combinations of cultivations were tried (Donald 1990). Control was generally better in drier areas and dry years than in higher rainfall areas. Differences in response from different clones were observed (Hodgson 1964). On an organic farm in Germany Pekrun & Claupein (2004) found that ploughing in autumn or winter was vital to control C. arvense, deep ploughing being more effective than shallow. Regular stubble tillage in summer and the inclusion of fodder crops in the rotation also helped to reduce this species.

Farmers in Sweden used fallowing and root and potato crops to combat thistle, their most difficult weed, since the exposed soil allowed cultivations during the growing season (Adolfsson 1996). Håkansson (2003) stated that thistle was less easily controlled by autumn tillage owing to dormancy then. In relation to ploughing, Magnusson, Wyse & Spitzmueller (1987) found that partially buried stem sections, both aerial and subterranean, taken up to the post-bloom stage were capable of developing adventitious roots and overwintering until the following spring. Sections taken in autumn did not survive the winter and survival rates were also lower in sections taken in spring or at the bud stage. When completely buried very few sections from any growth stage survived. Dock Gustavsson (1997) showed that short (7 cm) root segments and deeper burial could reduce regeneration compared with longer segments.

Rotations

Crop rotations have been used in the control of thistles by employing the different ecologies of crops to combat weeds. The introduction of leys into formerly continuous cereal rotations in Sweden in the 19th century gave better control of thistle though late cutting resulted in less suppression than the present-day early cuts for silage (Håkansson 2003). On the other hand, a cropping and short-term pasture rotation proved to be ideally suited in New Zealand for a rapid spread of thistle; the regular cultivation spread the roots and kept the soil loose, favouring rapid underground development. Cropped areas allowed flowering and seeding without any suppression from grazing (Saxby 1952). In Canada, 3–5 years of forages before corn or soyabean were recommended to reduce infestations. Choice of crop was important: thistle increased under wheat and soyabean but decreased under lucerne. Vigorous crop growth was the aim by means of the correct variety, cultivation, soil fertility and management (Doll 1981). Hodgson (1958) found that rotations of row crops with inter-row cultivation plus 2,4-D application could eradicate thistle. Hill, Patriquin & Vander Kloet (1989) recorded an increase in thistle to dominance over 4 years of an oats/clover/winter wheat/faba bean rotation in Nova Scotia without herbicides or fertilizers. Continuous maize in Slovakia led to higher thistle density compared with rotation with other crops (Demjanova et al. 2008). On an organic farm in north Germany repeated stubble tillage with a forage crop reduced thistle in the short term better than repeated mowing of a grass-clover ley or a forage crop/grass rotation. In the long term different cultural strategies showed only minor differences in thistle control (Lukashhyk, Berg & Kopke 2008). A significant increase in thistle occurred in spring barley grown in a 6-year organic (ecological) rotation in west Slovakia compared with a low input system (Macak et al. 2008). Brant et al. (2004a) recorded highest figures for thistle biomass production in naturally regenerated fallow in alternative rotations: 1.33 t ha−1 in the first year, 2.45 t ha−1 in the second year and 3.69 t ha−1 in winter wheat after fallow. Lolium multiflorum and Sinapis alba greatly reduced thistle biomass.

Competition

At the seedling stage, C. arvense is very susceptible to reduced light from shading and competition from neighbouring plants, particularly in grassland (Edwards, Bourdôt & Crawley 2000) but also within crop stands (Bakker 1960). Emergence is highest in bare ground or open spaces (Amor & Harris 1975). Shoots of established thistle plants also suffer from the competition of taller or more rapidly growing vegetation such as docks and nettles, or shrubs and trees within a hedgerow or woodland. Shade reduces root vigour and flower development (Lund & Rostrup 1901) and C. arvense is unable to grow under the closed canopy of mature woodland (Rodwell 1991a). Competition is clearly greater if the neighbouring plants are taller when the thistle shoots are at the early stages of emergence such as within crops of wheat or lucerne (Donald 1990; Bostrom & Fogelfors 1999). Vegetative spread in 2 years was greatly reduced by shading from dense Phragmites australis and was completely inhibited when this was combined with moist soil up to 5 cm from the surface (Bakker 1960). Grasses usually offer insufficient competition; lucerne or sweet clover are recommended in North America (Schreiber 1967), especially lucerne. Jones (1933a) found perennial ryegrass or ryegrass-abundant mixtures more competitive than Trifolium repens or so-called bottom grasses (Cynosurus cristatus and Poa trivialis), which he attributed to the earlier spring growth of ryegrass. Competition from ryegrass was much less where it had been weakened by heavy winter or early spring grazing. Conversely, once ascendant above other plants, thistle shoots can compete strongly, aided greatly by the reserves of their perennating storage roots.

Competition from Festuca arundinacea in combination with insect attack can suppress thistle in biological control (Ang et al. 1994b; Section XI). Bicksler & Masiunas (2008) used Sorghum sudanense (Piper) Stapf. in organic cropping systems to manage thistle. Lolium perenne or forbs reduced thistle vigour colonizing field boundary sites of arable fields in the Netherlands (Kleijn, Joenje & Kropff 1997), though, in fenced field margins in fertile UK grassland, C. arvense often rapidly dominates the ungrazed herbage (Cole et al. 2007). Establishment of perennial grasses in Nebraska, USA, pastures resulted in 90% control of thistle and was as effective as clopyralid application (Wilson & Kachman 1999). Hybrid wheatgrass Agropyron repens (L.) P. Beauv. X A. spicatum (Pursh) Schrib F5 hybrid provided the highest control. In grazed fields, thistle negatively affects the yield potential of neighbouring grass plants (Grekul & Bork 2004). In container trials Eerens et al. (2002) recorded highest thistle biomass (shoot + root) when there was no grass and clover competition and lowest at the highest level of sward competition.

V. Response to environment

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

(A) Gregariousness

Shoot density

The growth habit of C. arvense leads to a clumped distribution of aerial shoots with widely varying densities, originating from a single seedling or root fragment. In natural communities (Rodwell 2000) this results in clumps of shoots, except in very closed vegetation. Schreiber (1967) planted thistle shoots at 0, 5.4, 10.8, 21.6 m−2 in lucerne and found that after an initial increase in density, all stands approached 10.8 m−2 in plots not treated with herbicides. A density of 400 shoots m−2 was recorded in experimental culture in Alberta by Nadeau & Vanden Born (1990). Average shoot densities in North American crops generally varied from 0.2 to 7 m−2, though field densities of 1–40 shoots m−2 are achievable, with maxima up to 62 m−2 (Donald 1990). After the application of control measures (herbicide or mechanical), reduced populations of smaller, weaker shoots can result in the following year. These will rapidly form the basis of stand renewal unless follow-up measures are applied (Wilson 1981b). In Manitoba Kirkland (1977) recorded 52 m−2 in cereals after summer fallow. Thomas & Donaghy (1991) found an average of 4.4 shoots m−2 and a maximum of 48 m−2 in a survey of spring annual crops. Donald & Prato (1992) recorded 42 shoots m−2 in reduced-till cereals. Donald (1994b) used geostatistics to prepare contour maps of shoot density in established stands of thistle; areas of greatest shoot density had greatest underlying root mass, often with highest root bud number and more deeply growing root mass. Eber & Brandl (2003) recorded distribution and patch dynamics in a 15 km2 area over 5 years in N.E. Bavaria for their effects on insects. There were many more small patches than large and a 50% increase in patch numbers over 5 years, but decreases in plants per patch to less than half that in the first year. The extinction probability of a patch was negatively correlated with its size. Seasonal changes in experimental thistle shoot populations were measured by Belde et al. (2002) who found increases of 60% and 70% respectively when changing from conventional to integrated or organic farming systems. A simulation model of spatial distributions in arable and fallow land was developed, trying to identify the causes of increase (Belde & Mayer 2002). Leathwick et al. (2006) studied populations of 16–144 shoots m−2 planted in sterile soil in boxes. Growth of individual shoots was retarded as densities increased, primarily by reducing the formation of new roots and consequent reduction in aerial shoots. However, the density and germination rates of root buds were independent of plant density. There is no evidence of auto-competition within tall and vigorously growing thistle in a dense arrangement.

Surveys on grassland across the UK indicated average shoot densities of 0–10 (20) m−2 (Dow AgroSciences, unpubl. data). Edwards, Bourdôt & Crawley (2000) monitored shoot densities over 15 months following different cultivation and grassland management treatments. A maximum density of 61 m−2 was observed on cultivated plots grazed by rabbits, falling later to 38 m−2. Densities of 0–4 m−2 on uncultivated grassland were reduced where the herbage was ungrazed or fertilized but were increased when the herbage was removed by herbicides or heavy rabbit grazing, or when there was soil disturbance. Pywell (2006) reported densities of 14.3 ± 1.1 and 11.1 ± 0.7 m−2 in severe thistle infestations of semi-improved grassland at a lowland and upland site respectively. In areas of low infestation on the same sites, mean densities were 1.4 ± 0.29 and 1.9 ± 0.30 shoots m−2. Shoot biomass varies spatially, and field observations in UK permanent pasture indicate an annual flux of density, vigour and height; dense patches in one year become less dense and vigorous in the following year and vice versa. There is scope for long-term demographic studies under constant management conditions to describe growth behaviour more fully.

Dispersal of thistle achenes is predominantly adjacent to the parent plants, through gravity, shaking and overwinter decay of capitula. Hence if seedlings became established, population densities would increase, though this does not normally occur since germination is often very low and erratic. Growth of the root system is the more aggressive and successful means of invasion or increase in stand density (see VI C). Progress is rapid from seedling to perennation and vegetative spread of established plants by proliferation of the root system. An initial single stem can rapidly multiply to a patch within 2 years, with progressive expansion in the absence of effective control (Hansen 1918). Amor & Harris (1975) confirmed a poor establishment from seeds in pasture. Shoot height and density was greatest at c. 3 m from the advancing front of a thistle patch, there being a decrease towards the centre, suggesting senescence. Drought could also cause patches to become ring-like. Eighteen-week plants grown in the field by Nadeau & Vanden Born (1989) averaged 26 above-ground shoots, 154 below-ground shoots and 111 m of rootsystem of > 0.5 mm diameter. A single plant grown in a 60 × 120 × 240-cm box developed 71 above-ground shoots, 4.5 m length of underground rhizomes and 13.5 m of primary roots after 13 months (Ross & Lembi 1999, quoted by Hanson 2003).

(B) Performance in various habitats

Cirsium arvense can invade many different habitats (Morishita 1998). It was categorized as a competitive ruderal perennial by Grime (2001), present in the later stages of colonization of bare sites. Though primarily a weed of agricultural land – pastures, hayfields, cereal (Chancellor & Froud-Williams 1984; Steinmann 1999) and row crops – thistles are also characteristic of open vegetation, waste places, neglected land, including roadsides, railway embankments, stream and river banks, lakesides and ditches, abandoned fields (Lauringson & Talgre 2003), building sites, cleared swamps, woodland clearings and margins and hedgerows (Bakker 1960). Prach & Wade (1992) showed it was an ‘an ideal weed’ with a high expansive ability derived from a combination of a production of readily dispersed diaspores and efficient vegetative propagation. It characteristically occurs and grows well on deep fertile soils associated with agriculture and cropping (Hansen 1918; Fairbairn & Thomas 1959) and on areas of disturbance. It is intolerant of waterlogging, very dry conditions and shallow rocky soils. Creeping thistle flourishes on land neglected or under reduced management, e.g. set-aside fields or fenced off field margins and is a common weed of permanent pastures. In Canada it was less frequent in old prairies (Moore 1975). Detmers (1927) found maximum root extension in clay soils. Hodgson (1968) recorded the best growth in silt loam with deep, well aerated soil: growth was limited by high water tables and poorly aerated soil, as observed by Bakker (1960). Grime & Lloyd (1973) recorded thistle in the Peak District most often on slopes < 30° with a bias towards a southerly aspect. On chalk downland it invades areas made nutrient-rich by animal excreta, to the competitive detriment of low-growing short cropped species, and is present in tall, little-grazed communities on deep ex-arable soil (Smith 1980). Degradation of semi-natural pastures with ingress of thistle from local concentrations of animal excreta was also reported in Slovakia by Novak & Slamka (2003).

Owing to the seedling’s low competitive ability, successful invasion is primarily on cultivated, overgrazed or waste areas with disturbed soils and on open unmanaged sites (Edwards, Bourdôt & Crawley 2000; Hanson 2003), where its mode of spread and tall growth ensure rapid colonization and suppression of competing plants. Bakker (1960) found it rapidly became a serious weed on drained polder land. It became the most serious weed of irrigated crops in Nebraska (Wilson 1980). In the UK and Europe it is a frequent weed of set-aside, both long term and rotational (Fisher et al. 1992; Poulton & Swash 1992; Nemeth 2001; Stolcova 2002; Brant, Svobodova and Santruceck 2004b). Cirsium arvense invaded field boundaries over 15 years after a change from conventional to organic farming in Sweden (Lundkvist et al. 2008). In Finland (Salonen & Hyvonen 2002) it was one of the most abundant perennials in organic cropping where weed control was less intensive. In permanent pastures it was perceived as a problem on 20% of surveyed land in Northern Ireland (Courtney 1973) and on over 50% of surveyed farms in England and Wales (Forbes et al. 1980). Surveys in southern Britain (Hopkins et al. 1985) showed a more frequent incidence of C. arvense was associated with older swards, good drainage, grazed rather than cut fields, sheep-only and beef-only farms compared with dairy farms, and on land with little or no nitrogen fertilizer application; incidence was lower on fields receiving organic manures. A more extensive survey of lowland permanent grassland in southern Britain (Hopkins et al. 1985) confirmed that sward age was a consistent factor for thistle incidence together with a combination of winter grazing and low-intensity, rotational summer grazing. In the uplands (Hopkins et al. 1988) thistle was widespread especially in old swards, on steep land and on sheep-only fields with low or no fertilizer, though uncommon above 360 m. However, the proportion of grassland with a wide distribution of thistle reduced from 33% to 24% between 1972 and 1986, possibly due to herbicide use or more intensive management. In an east Scotland survey (Swift et al. 1983) half of all fields over 10 years old were heavily infested (defined as > 1 shoot per 16 m−2, equivalent to over 600 ha−1). It was absent from traditional haymeadows (Smith & Jones 1991; Tiley 2003). A 42% change of land use to dairying from sheep production may have been a factor in a recorded increase in thistle density on paddocks surveyed in 1984 and 2006 in the Lincoln district of Canterbury, New Zealand (Groenteman et al. 2006). Good light is required and Bakker (1960) observed that plants in 35–45% daylight produced fewer flowering shoots, heads and seeds, which showed very low germination. The contrast between the reduced growth of shoots in areas surrounded by trees or developed in tall wheat from an autumn-sown crop and those in open habitats was noted by Lund & Rostrup (1901). There were less pronounced central and weaker secondary veins on the leaves and relatively longer petioles. The blades were thinner, devoid of spines, hairs and undulations, lacked palisade tissue, epidermal calcareous deposits and had reduced chlorophyll.

(C) Effects of frost, drought, flooding, etc.

Frost

The aerial shoots are sensitive to frost and die in autumn and early winter (Lund & Rostrup 1901; Håkansson 2003). In the UK, flowering plants have generally senesced before winter frosts, but young vegetative shoots are susceptible in autumn; emerging shoots are not damaged by late spring frosts. Severe hard frosts can damage perennating roots and underground shoots close to the soil surface, but these readily sprout from lower down in the following spring. Soil cultivations to expose the roots to frost were considered to be a method of control (Brenchley 1915). Fragmented roots are more susceptible than those left undisturbed (Koch & Volf 1982). A study in Canada (Schimming & Messersmith 1988) determined LT50 (temperature to reduce the survival of roots by 50%) to be −7 °C; the GR50 (temperatures at which total dry mass (DM) of roots was reduced by 50%) was −5 °C. The results depended on the depth at which overwintering buds were located. Dexter (1937, cited by Schimming & Messersmith 1988) killed thistle roots by exposing them for 8 h to −6 to −8 °C. Ozer (1969, quoted by Koch & Volf 1982) found that root fragments were killed at −10 °C for 24 h and that −5 °C for 48 h reduced sprouting by 92%. Frost does not impair or influence the viability of ripened achenes, but can induce a pre-chilling benefit to germination (Kumar & Irvine 1971; Bostock & Benton 1979; VIII D).

Drought

Thistle roots possess considerable resistance to dry soil conditions, though rate and vigour of later growth can be reduced. Bakker (1960) found damping-off of seedlings at low moisture levels and recorded a reduction in vegetative increase in a dry environment. Masses of rhizome were reduced by dry growing conditions but recovered under more favourable conditions. Donald (1990) suggested that control was better with cultivations or rotations after drought years. There was reduced root biomass and shoot growth with fewer adventitious root buds after several years of drought. In continuous wheat shoot and adventitious root bud numbers decreased in the year following drought years (Donald & Prato 1992). Drought can affect the number of roots near the surface of well-watered sites. Lund & Rostrup (1901) found that horizontal roots remained near the soil surface, not deeper than 15–20 cm, in dry conditions but grew much deeper when the soil was moist and soft. Artificial drying of root cuttings to water contents of 20% or less severely reduced growth, with progressively fewer shoots produced as moisture stress increased (Hamdoun 1972). When comparing the growth and development of thistle root buds and shoots at high and low humidities, Hunter, Hsiao & McIntyre (1985) found 90–100% relative humidity (RH) increased shoot and root development by 50–80% and stem height by 50%. The rate of root bud emergence was increased and the length and DM of emerged shoots doubled after 7 days’ growth. Root buds were inhibited in mature stem tissue kept at low RH but not at high RH, indicating that competition for water between the root buds and main stem was the primary cause of correlative bud inhibition. Niederstrasser & Gerowitt (2008) found that root fragments exposed for 6 h on a dry soil in Germany failed to sprout when subsequently planted in pots whereas those exposed on a moist soil surface all sprouted when similarly planted. Minimum moisture levels are required for initial germination and subsequent seedling survival (VIII D; Bakker 1960).

Waterlogging

In spite of a preference for moister areas, C. arvense is intolerant of waterlogging or continuous inundation and is generally absent from swamp and aquatic communities, although it can survive temporary flooding (Rodwell 1995). The density and numbers of underground roots were reduced by raising the water table, causing the roots to damp off at low aeration levels, but seeds could germinate after 30 months of inundation (Bakker 1960). Roots of hydroponically grown seedlings grow abnormally, eventually with tip death (Sagar & Rawson 1964). Lund & Rostrup (1901) observed that the root system was weak and bunched when grown in water. Root cuttings flooded for 0–30 days showed progressive reduction in shoot formation to zero (Hamdoun 1972). However, dispersal via irrigation channels was contributory to the spread of thistle in North America (Bruns & Rasmussen 1953; Wilson 1980). Seedlings of thistle with two or six true leaves lost them after submersion for 8 weeks but some recovered when drained; a lower survival compared with typical marsh species was relatable to lower stem porosities (Lenssen, Ten Dolle & Blom 1998). Clearly, if at all practical, inundation could be a method of control. This was tried on a limited scale in the 19th century in New Zealand where flooding to a depth of 30 cm was reported to have eliminated creeping thistle (Saxby 1952).

Climate change

Insofar as climate change is increasing global temperatures, the latitudinal limits of C. arvense could be varied in future: northern and southern limits in the northern hemisphere may move northwards and the northern limit in the southern hemisphere may move southwards. In Sweden, Dock Gustavsson (1994) related the increased occurrence of C. arvense to the incidence of mild winters which improved the chances of overwinter survival followed by an earlier start to spring growth. The occurrence of new sites for C. arvense on the southern edge of distribution in Tennessee, where hitherto there were fewer than 190 frost-free days, could be a result of climate change (Sudbrink, Grant & Lambdin 2001). Measuring an increased cover by 5- to 13-fold of xerophytic Eurasian species, including C. arvense, on simulated drought and prescribed fire treatments on Alberta wetland, Hogenbirk & Wein (1991) hypothesized that a warmer and drier climate could lead to a greater frequency of this species.

The potential effects of climate change on the growth and behaviour of C. arvense have been studied by Ziska (2002, 2003a,b) and by Ziska, Faulkner & Lydon (2004). The effects of increased CO2 concentrations were studied (Ziska 2002) in growth cabinets using concentrations corresponding to 1900, 2001 and projected 2100 levels (285, 382 and 721 μmol mol−1). The estimated 2100 level of CO2 produced higher photosynthetic rates and increased numbers and lengths of spines; spine number and lengths were a function of CO2 concentration. A 69% increase in biomass was recorded for the estimated 2100 level relative to current ambient CO2 level. However, 2001 levels increased biomass by 126% compared with 1900 levels. It was concluded that increases in CO2 in the 20th century may have already significantly stimulated growth and photosynthesis and altered leaf defences against grazing. Comparing C. arvense with five other invasive species in USA in this research showed that C. arvense gave the largest response to increased CO2 levels. Biomass increased by 180% from 1900 to 2001 CO2 levels and by 72% from 2001 to 2100 levels (Ziska 2003a). The response to different concentrations of CO2 was independent of nitrogen availability (Ziska 2003b). In 2000 and 2001 field experiments (Ziska, Faulkner & Lydon 2004), CO2 concentrations of 350 μmol mol−1 above ambient produced significant increases in root and shoot biomass 2 months after emergence. Increases were 2.5–3.3 times greater for below-ground parts and 1.2–1.4 times greater for the shoots, thus increasing root/shoot ratios and potentially enhancing the resilience of the species. The effects of glyphosate herbicide on the roots were decreased, possibly a dilution effect, suggesting that C. arvense could be more difficult to control at higher CO2 levels.

Pollution

Studying the effects of ozone on UK wild species, Bergmann, Bender & Weigel (1999) found that C. arvense was one of the most sensitive to increased O3 concentrations (less than 1500 ppb). It would be a suitable species for biomonitoring the occurrence of this gas because of its clear damage symptoms (small whitish stipples on the leaves), rapid response, low threshold concentration, almost linear relation between dose and extent of injury, and a wide representation in the European flora. Power & Ashmore (2002) also reported the rapid development of symptoms from ozone exposure. There were large and significant reductions in photosynthetic rates, with effects on stomatal conductance. Biomass was reduced differentially above (42%) and below (58%) ground, giving a lower root : shoot ratio.

VI. Structure and physiology

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

(A) Morphology

Development of the adult plant has been described by Lund & Rostrup (1901), Hayden (1934), Bakker (1960), Sagar & Rawson (1964), Moore (1975), Holm et al. (1977) and Hoefer (1981). Within 6–10 weeks from germination a seedling bearing two foliage leaves develops a tap root with slender fibrous branches (see VIII D). The main root soon thickens with accumulating food reserves and root buds begin to initiate lateral stem shoots which run obliquely vertically, horizontally or arching upwards to emerge from the soil (Fig. 4). Most of these root-borne adventitious shoots occur in the upper 30 cm of soil and may be curled or twisted when the soil is hard or compacted (Hayden 1934). These shoots are histologically stem structures, which are sometimes termed rhizomes but Donald (1994a) preferred the term adventitious shoots and the buds from which they arise, adventitious root buds.

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Figure 4.  Six-month-old Cirsium arvense plant with thickening roots, root bud initials and two new developing vertical shoots.

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Roots

The main vertical root also produces one to four lateral roots (‘multiplication roots’ of Lund & Rostrup 1901) which spread out horizontally arching upwards or downwards in a concave manner before turning vertically downwards in an abrupt bend. The root achieves maximum thickness in this region, which is where leafy buds originate to produce new vertical adventitious shoots. A new horizontal multiplication root is almost always generated at the bend growing in the same direction as the mother root, repeating the cycle after horizontal extension growth, and resulting in rapid spread under favourable conditions (Lund & Rostrup 1901; Rogers 1928; Fig. 5). Histologically, these are roots which soon become thickened to form underground storage organs for perennation. The absence of nodes, internodes and scale leaves, a single central stele, endogenous origins of branches and exarch differentiation of the xylem which progresses centripetally all serve to characterize the network as roots (McAllister & Haderlie 1981). Penetration of the soil by roots is much deeper than by rhizomes, enabling escape from temperature extremes and mechanical disturbance. Roots are also more brittle than rhizome/stem tissue allowing a potential for a larger number of new plants, since shoots can regenerate from any point on the root.

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Figure 5.  Root distribution of adult Cirsium arvense, showing descending vertical roots (v), horizontal creeping roots (h) and adventitious root buds (b). (dr) Dead roots and (ds) dead shoots from previous season; (f) base of vertical flowering shoot. After Lund and Rostrup (1901), with permission of the Royal Danish Academy of Sciences and Letters.

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The horizontal roots growing laterally are responsible for spatial spread but bear few absorbing rootlets, live independently of the deeper growing vertical roots and carry more buds. The thinner absorbing feeding fibrous roots occur mainly on the descending vertical roots, which are important for water absorption, and at the nodes of vertical shoots originating from adventitious shoots, or from the main root (Hayden 1934; Moore 1975). The horizontal and vertical roots are the most important for carbohydrate storage during summer and the outer cortex occupies more than half of the root diameter (Rogers 1928).

The roots maintain their direction of growth unless obstacles are encountered; these may be bypassed before resuming the original direction, or channels of lower resistance are found, such as soil cracks or rotten tree roots. Root branches become generally weaker with greater distance from the main root, though they are uniform for much of their length. Size varies with soil type, being greatest in clay. In gravel, sand and marl or with hard pans and high water tables, bunches of small roots are produced, partly due to poor top growth and partly from frequent branching (Lund & Rostrup 1901). Investigating the longevity of roots, Bourdôt, Leathwick & Hurrell (2000) mowed thistle stands weekly to minimize photosynthesis and the formation of new root biomass. A very low proportion of overwintering root biomass remained after successive years of the experiment (6% and 10% respectively), supporting the hypothesis that the storage roots do not survive beyond the summer following that in which they were formed.

Shoots

Adventitious root buds capable of development into adventitious shoots can arise at any point on thickened roots (Thind 1975; Donald 1994a). This property bestows a highly flexible and very high potential for regeneration and is the principal characteristic ensuring the persistence and success of creeping thistle (Nadeau & Vanden Born 1989). After an adventitious shoot emerges from the soil, fibrous nutrient-absorbing roots develop near the soil surface. From an initially narrow diameter rosette of leaves, the shoot rapidly elongates in the main growing season to a normally unbranched flower-bearing main stem. Shoots emerging in late summer remain as short rosettes or medium height stems until killed by frost in contrast to earlier flowering stems which senesce naturally. If the stem is cut or damaged, the upper axillary buds develop branch stems which may bear flowers if sufficiently vigorous and day-length thresholds can be met or the flowering stimulus can be translocated. Leaves at the base and top of the stem are of smaller size than in the middle and the blade structure less complex. Leaf size depends on growth stage and growing conditions, being small in recently emerged shoots, maximal in the lower-middle of stems produced early in the season and minimal (2–4 cm) at the tips of lower-order axillary branches developed late in the season. The fully developed main stem terminates in early summer in an inflorescence of capitula, each borne on a narrow pedicel and developing sympodially. Capitula also develop later from the upper axillary branches in a loosely corymbose arrangement. In late summer axillary buds develop progressively down the main stem to short side branches with smaller, often paler, leaves and depauperate terminal inflorescences.

Anatomy

A summary of root anatomy and root bud development was given by McAllister & Haderlie (1981). Thind (1975) found both diarch and triarch xylem arrangements in the primary roots, though Hamdoun (1970b) found only diarch xylem with two protoxylem poles. The pericycle opposite the protoxylem poles gives rise to both lateral root initials and adventitious root buds. These are difficult to distinguish under the microscope in the early stages but by the time of emergence an adventitious root bud is several times the size of a lateral root initial (Thind 1975). Latex vessels are present in the roots and young shoots. Fibrous roots originate in the interfascicular cambium between the vascular bundles of the shoot. Storage roots develop a thick cortex for carbohydrate reserves. There is limited secondary growth of xylem and phloem in the older roots but they do not become woody. The epidermis becomes dark and impregnated with suberin and the cortex is persistent (Hamdoun 1970b; Thind 1975). The root system of creeping thistle is constantly being renewed as new roots take the place of those which die. A new root in the spring will be fully developed at the end of summer before going on to produce an inflorescence-bearing shoot in the following year, after which it slowly dies and decays. Individual roots probably do not survive more than 2 years unless development has been interrupted through damage, smothering or other influence (Rogers 1928; Sagar & Rawson 1964; Moore 1975; Bourdôt, Leathwick & Hurrell 2000).

According to Lund & Rostrup (1901), the stem carries 50 vascular bundles, three large and many small serving each leaf. The central pith gradually disappears leaving a cavity. Near the stem tip there is a white latex which becomes more abundant just before the capitula develop. The stem is normally straight with internode length varying from zero in the rosettes up to 9 cm, especially in plants in deep shade. The leaf has a well-developed vascular system with veins prominent on the lower surface. The cell walls in the upper epidermis are straight. On the lower epidermis they are slightly sinuous, but of zig-zag shape in the cotyledons (Fig. 6). Bundles of raphides (needle-like crystals of calcium oxalate) are deposited in the epidermal cells. The angle of divergence of leaf insertion is 3/8. Leaf undulations are developed by more rapid growth at the edge than near the veins. These are more accentuated in first-order leaves, reducing in size in later orders. Leaf histological features were demonstrated in photomicrographs by Solymosi (2007). The early stages of development of the inflorescence scales are the same as for the leaf, before being later distinguished by the lack of chlorophyll, of palisade tissue and of calcareous deposits in the epidermal cells (Lund & Rostrup 1901).

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Figure 6.  Epidermal cells from Cirsium arvense (a) cotyledon, upper surface; (b) adult leaf, upper surface; (c) cotyledon, lower surface; (d) adult leaf, lower surface. After Lund and Rostrup (1901), with permission of the Royal Danish Academy of Sciences and Letters.

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Hodgson & Moore (1972) found that the average size of stomata did not vary among clones but stomatal area (area of stoma + area of guard cells) varied significantly: 1.88–2.92 mm2 cm−2. Clone and temperature of site had significant effects on the ratio epidermal cell number : number of stomata (ESR).

(B) Mycorrhiza

Harley & Harley (1987) record two occurrences of arbuscular mycorrhiza from the UK and another from Poland. Daft & Nicolson (1974) referred to Endogone spp. [now known to be Glomus spp. (Glomeromycota)] as the predominant endophytes colonizing roots of C. arvense on a coal spoil tip (‘bing’) in west Scotland. A second, unnamed fungus with narrow hyphae [almost certainly G. tenue (Greenall) I. R. Hall] was also recorded. The mean total colonization level was 33.5% of root length. It was noted that C. arvense was in a group of species showing a limited growth of root hairs so that the presence of mycorrhiza could improve the efficiency of P uptake in this pioneering plant. Klironomos (2002) observed a positive effect on the growth of C. arvense from colonization by arbuscular mycorrhizal fungi. The ability of these fungi to slow the build-up of plant pathogens was also considered to contribute to its abundance in new habitats. Gange & Nice (1997) observed mean mycelial colonization levels of 56.3% by arbuscular mycorrhiza in roots collected in south-east England. Colonization could be suppressed by the application of fungicide or by N-fertilization. Heights were reduced by fungicide but shoot number was not increased, whereas both were increased by fertilizer. Bajwa, Shafique & Shafique (2006) found that heavy infection by Puccinia punctiformis (Str.) Röhl. did not affect mycorrhizal colonization of C. arvense roots. The development of vesicles, which are involved in storage, was significantly enhanced but numbers of arbuscules, which are the sites of metabolite exchange, were suppressed. Moderate rust infections showed only small effects on levels of arbuscular colonization. It seems likely that arbuscular mycorrhiza will occur widely on C. arvense in natural communities (D.J. Read, pers. comm.).

(C) Perennation: reproduction

After flowering and seeding, the mature stem dies back into the upper soil layers and C. arvense overwinters via the extensive underground storage root system and remnants of the vertical adventitious shoots until the following spring. Any plant parts in the upper soil are susceptible to penetrating frosts. The majority of viable seed produced overwinters in the dormant state until the onset of the relatively high temperatures of the following season. Some seeds may germinate during the late summer and form plant rosettes which overwinter as buried roots (Moore 1975). Seed production and dispersal are the primary modes of distribution over distances, augmented by transport of soil containing root fragments. Local increase and spread are achieved through highly effective root propagation (Hayden 1934; VI A). Strobach, Korcakova & Mikulka (2008) showed that plants developed from vegetative parts give rise to greater above-and below-ground biomass than plants developed from seedlings. Growth measured from April to October in plants derived from seedlings or vegetative parts produced 167.5 and 226.8 g, respectively, biomass above-ground, 117.5 and 241.6 g below-ground, rootstock length of 15.59 and 35.94 m, and aerial shoot height of 24.0 and 44.0 cm.

Flowering and seeding

Cirsium arvense is a long-day plant requiring 14–16 h photoperiods (Moore 1975). Bakker (1960) found that seedlings have a juvenile, vegetative period before flowering is possible, although Donald (1994a) observed that plants can flower in their first season after seedling emergence. Gibberellin was reported to stimulate bolting (stem elongation) under short photoperiods (Sterrett & Hodgson 1983). Thistle plants are either female (pistillate) or male (staminate) and are considered to be dioecious. However, male plants occasionally bear hermaphrodite flowers and produce seed, though this is smaller and less viable than on female plants. Lloyd & Myall (1976) thus describe C. arvense as near-dioecious, falling short of strict gynodioecy because of the low seed set on male plants and because most male stems produce no fruit (VIII C). Research into dioecy and its evolution in the genus Cirsium was reviewed by Delannay (1979).

For fertilization and production of viable seed, staminate and pistillate clones must be growing in close proximity to allow insect pollination, which is mainly by bees and butterflies but occasionally by other insects (Table 2). Ellis & Ellis-Adam (1992) listed numerous insects visiting thistle flowers in the Netherlands. Isolated clones are unable to set seed (Kay 1985). Lalonde & Roitberg (1994) found that seed set in females was constrained by availability of pollen. Female patches separated from males by at least 50 m set far fewer achenes per head than female plants interspersed with males and the distance to nearest effective pollen donor correlated negatively with fertilization. There was a partial compensation for lack of pollen by maintaining the stigmas longer in a receptive state. Hayden (1934) found good seed set where male and female plants were within 33 m, but very little at distances of 160–200 m. Amor & Harris (1974) found some seed set at separation distances of up to 390 m. Other maximum distances reported include: 180 m (Detmers 1927) and 50 m (Bakker 1960). In glasshouse studies, wind pollination resulted in only 0.21 and 0.76 seeds per head compared with 45.6 and 43.5, respectively, after pollination by bees (Derscheid & Schultz 1960). Numbers up to 83 (Derscheid & Schultz 1960) and 98 (Hayden 1934) seeds per head have been recorded.

Table 2.   Insect visitors recorded from Cirsium arvense flowers
Species (by order and family)Source
  1. Source: 1, Müller (1883); 2, 3, 4, Knuth (1908)– 2, observed by Knuth; 3, observed by Müller; 4, observed by other observers; 5, Ellis & Ellis-Adam (1992).

Coleoptera5
Cerambycidae
 Strangalia melanura (L.)3
Curculinoidae
 Bruchus sp.1, 3
Mordellidae
 Mordella aculeata L.1, 3
 M. fasciata F.1, 3
Scarabacidae
 Cetonia aurata (L.)3, 4
 Trichius fasciatus (L.)2, 3
Diptera5
Conopidae
 Conops flavipes L1, 3
 C. quadrifasciatus De Geer3, 4
 Physocephala rufipes (F.)1, 3, 4
Empidae
 Empis livida L.1, 3, 4
Larvaevoridae
 Oliviera lateralis F.1, 3
Muscidae
 Calliphora erythrocephala (Meigen)4
 C. vomitoria (L.)2, 4
 Coelopa frigida (F.)2
 Cynomya mortuorum (L.)4
 Lucilia caesar L.2, 4
 L. sericata (Meigen)1, 3
 Musca corvina F.1
 Nemotelus uliginosus (L.)2
 Nemoraea pellucida Meigen4
 Ocyptera brassicaria (F.)1, 3
 Rivellia syngenesiae (F.)2
 Sarcophaga carnaria (L.)1, 2, 3, 4
 Scatophaga merdaria F.2, 4
 S. stercoraria L.2, 4
 Stomoxys calcitrans (L.)4
Platystomatidae
 Platystoma seminationis (F.)1, 3
Stratiomyidae
 Odontomyia hydroleon (L.)4
 O. viridula (F.)3, 4
Syrphidae
 Eristalis aeneus (Scop.)1, 2, 3
 E. arbustorum (L.)1, 2, 3, 4
 E. intricaria (L.)1, 2, 3, 4
 E. nemorum (L.)1, 2, 3, 4
 E. pertinax (Scop.)2
 E. tenax (L.)1, 2, 3, 4
 Helophilus pendulus (L.)2, 4
 Platycheirus manicatus (Meigen)4
 Syritta pipiens (L.)1, 2, 3, 4
 Syrphus ribesii (L.)2
 Syrphus sp.1, 3
 Volucella bombylans.var. plumata Macq.2, 3
 V. bombylans.(L.)4
 V. manis (L.)3
 V. pellucens (L.)2, 3, 4
Tabanidae
 Tabanus bromius L.3
 T. rusticans L.1, 3
Hymenoptera5
Apidae
 Andrena bimaculata K. var. vitrea Sm.3
 A. flavipes Pz.4
 A. florea F.4
 A. fulvicrus (K.)1, 3
 A. nana (K)1, 3
 A. nigriceps (K.)4
 Anthophora quadrimaculata (Panzer)2
 Apis mellifica L.1, 2, 3, 4
 Bombus agrorum (F.)2
 B. hortorum (L.)1, 3, 4
 B. lapidarius (L.)1, 2, 3, 4
 B. lucorum (L.)4
 B. ruderatus (F.)4
 B. soroënsis var. proteus Gerst.2
 B. sylvarum (L)4
 B. terrestris (L.)2, 4
 Cilissa leporina Pz.1
 Coelioxys conoidea (Illiger)4
 Dasypoda hirtipes (F.)1
 Epeolus variegatus (L.)1
 Halictus albipes (F.)1, 3
 H. cylindricus F.1, 3
 H. flavipes F.1, 3
 H. longulus Sm.1, 3
 H. maculatus Sm.1, 3
 H. minutus K.1, 3
 H. nitidiusculus K.1, 3
 H. nitidus Schenck3
 H. rubicundus (Chr.)1, 3
 H. tarsatus Schenck1, 3
 Heriades truncorum (L.)1, 3
 Macropis labiata (F.)3, 4
 Nomada fabriciana (L.) var. nigrita Schenck1, 3
 N. jacobaeae Pz.1, 3
 N. lineola Pz.1, 3
 N. robertjeotina Pz.1, 3
 N. solidaginis Pz.1, 3
 Prosopis communis Nyl.1, 3
 P. confusa Nyl.1, 3, 4
 P. sinuata Schenck1, 3
 P. variegata (F.)1, 3
 Psithyrus quadricolor Lep.2, 4
 P. rupestris (F.)4
 P. vestalis Geoffroy4
 Sphecodes gibbus (L.)1, 3
Chrysidae
 Hedychrum lucidulum (F.)4
 Holopyga amoenula Dahlb.4
Formicidae
 Formica fusca L.4
Ichneumonidae
 Several species1, 3
Sphegidae
 Ammophila sabulosa (L.)1, 2, 3
 Cerceris arenaria L.1, 3, 4
 C. rybiensis L.4
 Crabro cribarius (L.)1, 3
 Dinetus pictus (F.)1, 3
 Lindenius albilabris (F.)1, 3
 Oxybelus mucronatus (F.)4
 O. uniglumis (L.)1, 3, 4
 Philanthus triangulum F.1, 3
 Passaleucus brevicornis F.4
Vespidae 
 Vespa vulgaris (L.)3
Lepidoptera5
Nymphalidae
 Argynnis aglaja (L.)4
Noctuidae
 Plusia gamma L.2
Rhopalocera
 Epinephele hyperanthus L.3
 E. janira L.2, 3, 4
 Hesperia comma (L.)4
 H. lineola (Ochs.)3
 H. sylvanus Esp.1, 3
 Melanargia galathea L.4
 Pieris brassicae L.1, 2, 3, 4
 P. napi L.2
 P. rapae (L.)2
 Satyris janira L.1
 Thecla rubi L.1, 3
 Vanessa io (L.)4
 V. urticae L.1, 2, 3
Sphingidae
 Zygaena filipendulae2
Vegetative reproduction

Vegetative spread can occur in two ways (Hayden 1934): vertical adventitious shoots can produce root and shoot branches at any node; horizontal and vertical roots can develop root branches or adventitious shoots at any point. Roots have a potential to produce more plants than the vertical shoots, which have buds only at internodes c. 5 cm apart. Only one bud will normally grow from a piece of adventitious shoot bearing several nodes, but all will grow if the stem is cut into separate nodes. On the other hand, segments of root cut to 1-cm (Hayden 1934) or 0.5-cm (Hamdoun 1972) lengths are each capable of producing adventitious shoot buds, immediately or after perennation. Growth from both shoot and root cuttings was greatly reduced when they were taken at the end of the flowering season, owing to exhaustion of food reserves. This was confirmed by Håkansson (2003) who suggested that a weak state of physiological dormancy set in during late summer. At this time the roots become brittle and turn brown before later becoming soft and black as they disintegrate at the end of their second year. As the roots die at the distal ends of the network, maintenance of plant population derives from the younger branches of horizontal roots producing new aerial shoots, though Hamdoun (1972) demonstrated a low capacity for regeneration from segments close to growing apices. He also showed that growth from 25- and 50-mm root fragments was prevented by temperatures below 5 °C, optimum growth occurring at 15 °C. There was successful emergence from 25-mm fragments at a depth of 50 cm. Thind (1975) confirmed that root and shoot buds can arise at any point along a horizontal root. The rate of horizontal root spread can be rapid if competition is minimal. Rogers (1928) reported up to 13 m or more in one season, Hayden (1934) reported 6 m and Bakker (1960) 4 m. In Australia Amor & Harris (1975) measured a rate of spread of up to 3.4 m per year, with an average 1.5 m. Shoot bud development is possible on thistle roots very early in the life of the plant, as young as 19 days (Wilson 1979). Hoefer (1981) measured a spread of 113 m2 in 2 years.

Though C. arvense roots are capable of penetrating to a reported maximum depth of 6.8 m (Rogers 1928), 5.5 m in loam soils in Russia (Malvez 1931, cited by Moore 1975), and 2 m, limited by water table in Iowa (Hayden 1934), the bulk of the branching system occurs in the upper 30 cm. A depthwise distribution of roots excavated by Hodgson (1968) is illustrated in Fig. 7. Hunter (unpubl. data, quoted by Hoefer 1981) observed 41% root mass at 60–90 cm soil depth. Nadeau & Vanden Born (1989) reported a normal rooting depth of 1.8 m, with most (75%) of the root system occurring below 20 cm, the usual depth of cultivations. Highest root concentrations per unit of soil volume for both total root length and root DM were between 20 and 40 cm depth. On average, the root system of an 18-week-old plant could potentially produce 930 shoots if cut into 10-cm lengths (see V A).

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Figure 7.  Distribution of Cirsium arvense roots down the soil profile. Data from Hodgson (1968).

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(D) Chromosomes

A chromosome number of 2n = 34 was quoted for Cirsium arvense sensu lato and for all four varieties by Moore & Frankton (1974).

(E) Physiological data

Production and storage of root reserves for overwintering

North American studies on photosynthesis, translocation and carbohydrate accumulation were summarized by Haderlie & McAllister (1981). They quoted work by Desai & Renney (1968) who found an optimum rate of photosynthesis at 20 °C, decreasing to only one-third (3.8 mg CO2 g−1 h−1) of this at 30 °C, which implies a better adaptation to temperate than tropical conditions, in a C3 plant (Håkansson 2003). A rapid rate of photosynthesis was reported in late summer that could quickly replenish root reserves. Zimdahl, Lin & Dall’Armellina (1991) found that an experimental reduction in light availability reduced shoot and root DMs, leaf area and inflorescence number; the greatest effect of light was on inflorescence production which ceased below a light flux of 30 μmol m−2 s−1. The major compounds occurring in the leaf after treatment with 14C-labelled CO2 were sucrose (52%), asparagine (10%), malic acid (10%) and five amino acids (18%). Rogers (1925, cited by Haderlie & McAllister 1981) found a minimum carbohydrate level of 29% in June and a maximum of 64% in December. Organic reserves in thistle roots were studied through three seasons in Ohio, USA, by Welton, Morris & Hatzler (1929). DM contents of roots were lower in spring than in autumn, reaching a minimum at about 1 June, followed by a rapid increase from July onwards. Content (%) of easily hydrolysable carbohydrates followed a similar pattern. Quantities of free reducing sugars followed an inverse trend, with rapid increases during vigorous growth in early season, then falling. Levels of inverted sugars were high in March before shoot emergence, declining markedly in April, remaining low during the period of rapid growth and then rising again in July after plant maturity. Hodgson (1968) found carbohydrate root reserves increased with depth in the soil. Results from weekly samples, taken from April to October over 2 years, showed a decline from early spring to a minimum in June when the flower buds had begun to appear. Reserves then increased until levelling off in September. Data from Bakker (1960; Fig. 8), Sagar & Rawson (1964) and Wilson, Martin & Kachman (2006) support this. Seasonal variations in spring temperatures were considered to affect the pattern of utilization of root reserves (Hodgson 1968). Tworkoski (1992) found that more assimilate transferred to the roots at the stem elongation (bolt) stage than at the bud, flower or post-flower stages in the field. In growth cabinets, simulated early spring and autumn environments were more important than growth stage in governing the rate of assimilate transfer to the roots. He concluded that most assimilate is used in growth at the rosette stage and for root reserves at the bolt and flowering stages.

image

Figure 8.  Carbohydrate concentrations as water-soluble sugars after hydrolysis in Cirsium arvense roots from April to October. After Bakker (1960), with permission of Blackwell Scientific Publications Ltd.

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In roots excavated monthly in Nebraska Wilson, Martin & Kachman (2006) found 73% of total carbohydrates in October were fructans and 27% free sugars (of which 87% was sucrose). Sucrose and short chain fructans increased in autumn and remained high through the winter before falling as growth began in April. In colder winters sucrose levels were higher, associated with lower soil temperatures. McAllister & Haderlie (1985a) found that carbohydrate reserves were stored preferentially in the roots rather than in developing root buds or bases of shoots, and confirmed much higher contents (26% of fresh root mass) in autumn compared with the spring (3%). Contents of inulin, the main storage carbohydrate, fell to their lowest, 0.7–2.5% of DM, at the flower bud to flowering stage, a low content of inulin indicating the most suitable date for application of herbicides (Chodova & Mikulka 1986). Some storage carbohydrates were converted to sugars as early as February for use in root–shoot growth. Root reserves of DM, chiefly easily hydrolysable carbohydrates, were reduced temporarily by cutting but were quickly replenished in summer with even a few centimetres of shoot growth (Welton, Morris & Hatzler 1929). There could be a net loss of total non-structural carbohydrates in autumn if a renewal of root and shoot growth stimulated during warm spells utilized reserves after photosynthesis had ceased due to frost kill (Haderlie & McAllister 1981). Reductions could also result from the use of herbicides, e.g. 2,4-D and clopyralid going into winter (Wilson, Martin & Kachman 2006), or in spring, from damage by biological control agents (Hein & Robert 2004). Analyses of the carbohydrate components of thistle roots (Wilson, Martin & Kachman 2006) revealed changes in proportions of the soluble sugars (fructans, sucrose, 1-ketoses, 1-nystose) with soil temperature and clopyralid application. In the Wilson & Michiels (2003) work in Nebraska, investigating the success of autumn-applied herbicides, root contents of fructans with low degree of polymerization (DP) were reduced when dicamba was applied a week after the first frost, giving better control than 2,4-D, or dicamba before the first frost. As dicamba rate was increased, plant control increased, associated with increased activity of the enzyme fructan-1-exohydrate and decline of DP fructans.

Translocation pathways and function in relation to the efficacy of herbicides

The effects of photoperiod and shoot and root temperatures in controlled environments were studied by McAllister & Haderlie (1985b). Net assimilate translocation was greater at 13 than 15 h day length; increase in temperature had little effect unless there was a 7-day acclimatization period. Higher total root-bud elongation occurred with increased temperatures and longer photoperiod, being greatest at 30 °C root temperature and 15 h photoperiod combined with shoot temperatures of 25 °C day/15 °C night. Root bud number was greatest at 20 °C root temperature. Highest DM production was at 30 °C day/22 °C night shoot temperature and 20 °C root temperature. Hunter & Smith (1972) found that numbers of shoot buds formed on root sections in the glasshouse and root–shoot ratios were inversely related to temperature (16–27 °C) and photoperiod (8–16 h). There was a change from root to shoot growth with increase in temperature and photoperiod, with flowering in 16 h days. The fates of 14C-labelled assimilate and glyphosate applied to mature leaves in mid-June were also monitored (McAllister & Haderlie 1985c). With a generally basipetal movement there were no differences in distribution, this being 25–31% in the roots and 58–59% in the shoots. A greater transport of assimilate from mature leaves occurred in the middle of the stem than from upper or lower leaves and root buds were the major sinks; assimilate transport to the roots was greater in older plants (MacDonald 1977, cited by Haderlie & McAllister 1981). Translocation rates were reduced when stem segments had been chilled, with differential effects according to clone origin (Geiger 1969, cited by Haderlie & McAllister 1981). Rates recovered in stem segments from a northern (Montana) clone after chilling to 0.5 °C but did not in a southern (Californian) clone; translocation rates could recover in both clones after chilling to 5 °C.

Nitrogen

Cirsium arvense in dense stands responds well to high nitrogen and thrives in fertile soils but the response is more variable in mixed communities where competition from neighbouring plants can be stimulated, as in grassland. Hamdoun (1970a) found a significant increase in the numbers of shoots per plant when N was increased. McIntyre & Hunter (1975) found seedlings in sand culture grew better in an ammonium nitrate than a nitrate solution but there was no difference in half sand : half soil or in hydroponic solution. Very low N was sufficient for growth but 100–200 ppm N was optimal. Cirsium arvense was very responsive to N supply, which increased DM yield and stimulated growth of root buds up to 210 ppm N. Numbers of root buds initiated were significantly reduced with increased N supply but their growth increased; numbers of shoots per unit area and per plant increased, though root–shoot ratios decreased. In Reece & Wilson’s (1983) trials, N application favoured the growth of thistle over that of the grass components since it used N more efficiently. Nadeau & Vanden Born (1990) confirmed that higher N increased shoot densities, associated with an increase in root growth rather than released root bud dormancy. Application of N was thought to increase the response to herbicides. Eerens et al. (2002) reported that fertilizers did not influence thistle development in high fertility areas. Dau & Gerowitt (2004) found fertilizer application with mowing led to a rapid decrease in shoot density and patch diameter within 2 years. Grekul & Bork (2007) confirmed that longer term (3 years) control was enhanced with annual spring fertilization when using clopyralid + picloram + 2,4-D. Fertilization without control (herbicides or cutting) decreased thistle density but increased biomass, whereas mowing once increased shoot densities.

Transpiration

Cirsium arvense transpiration rates during August in a German vineyard were the lowest among weed species, with low values in the morning and afternoon and peak values between 12.00 and 15.00 h (Lopes et al. 2004).

(F) Biochemical data

Mineral content

Gross chemical analyses of C. arvense have been reported from the standpoint of potential nutritive value as a livestock feed (Fairbairn & Thomas 1959; Barber 1985; Marten, Sheaffer & Wyse 1987; Harrington, Beskow & Hodgson 2008; SAC unpubl. data). Values for constituents are listed in Table 3. Calcium and potassium contents are noticeably high. Lehoczky et al. (2003) found high concentrations (2.2–5.9%) and uptake of potassium in roots and shoots, with nitrogen contents of 1.5–3.6%. Harrington, Beskow & Hodgson (2008) found that Cirsium arvense was capable of luxury uptake of potassium (excess above metabolic requirements). Protein contents of the leaves were also high (Barber 1985) and equivalent to those of forage legumes (Marten, Sheaffer & Wyse 1987; Harrington, Beskow & Hodgson 2008). Concentrations of sulphur and micronutrients (Fe, Zn, Mn, Cu, Co, B) were relatively high when compared with grasses (Harrington, Beskow & Hodgson 2008). But for its low palatability, creeping thistle would be considered an important source of minerals in forage herbs (Swift et al. 1990). DM content increases with maturity, accompanied by reduced digestibility, increased fibre levels and lower mineral concentrations. The apparently favourable mineral content was often considered likely by earlier authors (Fairbairn & Thomas 1959); this could be exploited to a limited extent by ensiling, or by cutting, wilting or bruising before grazing (Stapledon & Davies 1941).

Table 3.   Nutritional value and nutrient composition of Cirsium arvense shoots, on a dry mass (DM) basis
 Mature shootsShoots*Leafy shoot tipsMature shoots, organic pastures
Source1234
  Year 1Year 2  
  1. *Where ranges are given, higher values for D, protein and N, and lower values for fibre, are for younger stems (with good feed value); opposite range values are for older shoots.

  2. †Acid detergent fibre.

Total dry matter content (%)11.8
Nutritional value (% DM)
 Digestibility value (D) 64.4–76.471.8–79.266 
 Neutral detergent fibre1.5–4.840.9–50.427.6–33.8 24.7†
 Fat, ether-soluble2.4  8.2 
 Crude protein29.614.7–17.218.3–27.623.629.2
Macronutrients (%DM)
 N4.742.35–2.752.93–4.423.782.8
 P0.510.250.360.410.36
 K4.32.983.316.22.93
 Mg0.20.480.490.30.31
 Ca2.12.042.542.01.87
 S   0.360.57
 Na0.27  0.080.05
 SiO22.2    
 Cl3.3    
Micronutrients (ppm DM)
 Fe468186222126139
 Cu299121817
 Mn59665262120
 Zn 174313841.7
 B 24262629.3
 Co0.06   0.33
 Se    0.03
 Mo    0.21
 Al 248216  
Volatiles

Jordon-Thaden & Louda (2003) reviewed the literature on the chemistry of the genera Carduus and Cirsium, with reference to possible biological activity for insects. French et al. (1988) researched the chemistry of C. arvense in relation to thistle rust, Puccinia punctiformis (Str.) Röhl. Hexane extracts of thistle roots were found to be biologically active in stimulating germination of dormant rust teliospores. Chemical analyses showed the presence of C17 unsaturated hydrocarbons, with a concentration of 0.032 μg g−1 fresh matter of aplotaxene [(z,z,z) – 1,8,11,14-heptadecatetraene] in the fraction which showed the greatest stimulatory activity. This property however could not be confirmed using the synthetic chemical (French et al. 1988). The volatile components of thistle were identified by Binder & French (1994) using gas chromatography and mass spectrometry. Among 24 compounds identified were seven C13 polyacetylenes, seven unsaturated C15–17 hydrocarbons and five epoxides derived from C16 and C17 hydrocarbons. Exposing rust teliospores to volatiles from germinating thistle seedlings, French, Nelson & Binder (1994) were able to correlate increases in teliospore germination with increased output of C13 polyacetylenes from the seedlings. Volatiles collected from root cuttings also stimulated teliospore germination, indicating that the germination stimulus was adequately accounted for by the C13 polyacetylenes. A parallel study on volatile substances produced by rust-infected thistle plants identified four structurally similar compounds with well-known flavour, fragrance and insect attractant properties: benzaldehyde, phenethyl alcohol, phenylacetaldehyde and indole, the two latter being most abundant. Only benzaldehyde and indole occur in trace quantities in uninfected plants. Three of the four compounds (excepting indole) were prominent in the components of normal flower aroma. Phenylacetaldehyde was the main component at 10 times the concentration of benzaldehyde or phenethyl alcohol. Methyl salicylate and methyl 2-methoxy benzoate were also present in flower volatiles. All volatiles were structurally similar mono- or di-substituted phenyl compounds (Connick & French 1991).

Theiss & Raguso (2005) referred to 13 scent components in C. arvense and found an 89% decline in emission rates within 48 h of pollination. No insect repellent compounds were then emitted. Testing 10 components emitted by thistle flowers, Theiss (2006) found that the two dominant compounds, benzaldehyde and phenyl acetaldehyde, attracted both pollinators and florivores. The remainder attracted either pollinators or florivores. Testing the electrophysiological responses of the moth Autographa gamma (L.), Plepys et al. (2002) found 12 compounds from thistle flowers were consistently active. El-Sayed et al. (2008) identified 19 floral compounds in the volatiles produced by thistle flowers, including 55% phenylacetaldehyde, 14% methyl salicylate, 8% dimethyl salicylate, 4.5% pyranoid linalool oxide, 3.5% benzaldehyde and 14 other minor compounds. Testing the attraction of the main floral volatile, phenylacetaldehyde, it was found that higher doses of this compound increased the total catch and diversity of insects trapped. A 11-component blend of volatiles was the most attractive blend tested in the field and the authors concluded that C. arvense flower odours could be a generic insect attractant for monitoring invasive insect pest species.

Other compounds

The foliar waxes of thistle leaves were reported by Tulloch & Hoffmann (1982) to contain 35% esters, 12% hydrocarbons, 10% free alcohols, 8% triterpene and 3% free acids. Carbon chain lengths were: esters C40–50, free alcohols C24–30, free acids C24–28, but mainly C24. Hodgson (1973) reported differences in lipid extracts between clones in the United States and increases in lipids as plants progress from the floral bud stage to flowering. Dutta, Roy & Ray (1972) reported on the presence in thistle of taraxasterol and its derivatives. 3-O-methyl kempferol was identified by Shelyuta, Bubon & Glyzin (1972). A glucoside and other flavonoids were described by Wallace (1974). Antioxidant activity in methanol extracts from thistle leaves and inflorescences was measured by Nazaruk (2008) in Poland. Total phenol contents and antioxidant activity were positively correlated in methanol and ethyl acetate extracts. Further studies (Nazaruk et al. 2008) related contents of tannins and phenolic compounds in aqueous extracts to antimicrobial and antioxidant effects, with phenolic compounds being more active. The occurrence and distribution of growth hormones in thistle roots were quantified by Thind (1975). Auxins present were indoleacetic acid, indolealdehyde, indolecarboxylic acid, indoleacetonitrile, tryptophan plus an unidentified indole compound. Five gibberellins were identified in order of activity: gibberellins A3, A7, A1, A4 and gibberellin A8. The growth inhibitor abscisic acid was also isolated and identified from C. arvense roots. There was a seasonal variation in gibberellin contents, which were highest during summer, and in abscisic acid, which was highest in winter. The honeydew from Aphis fabae Scop. feeding on thistle was found to contain significantly higher amounts of total sugars compared with that derived from other host plants (Fischer, Volki & Hoffmann 2008).

Allelopathy

Though Donald (1994a) considered that allelopathy in thistle was not conclusively established, the possibility that it could contribute to competitive effects has been studied mainly by adding plant extracts to germinating seeds. In Tasmania water and ethanol extracts from the roots and foliage of C. arvense inhibited the germination of C. arvense and Trifolium subterraneum seed and slowed the growth of seedlings of three annual thistles, C. arvense, Hordeum distichon, Lolium perenne and T. subterraneum (Bendall 1975). The glasshouse study was prompted by the observed exclusion of annual thistles from areas of monospecific C. arvense. Wilson (1981a) also noted an inverse association between densities of thistle shoots and populations of other annual and perennial weed plants. The addition of 3% by mass of thistle root or stem residues to the soil reduced growth of a number of crop plants and of C. arvense itself. Autoclaving the residue or addition of fertilizers did not reduce residue toxicity. Similar results were reported by Stachon & Zimdahl (1980). Inhibition of germination and reduction in growth rates by tissue extracts were also reported by Kovacs, Mikulas & Polos (1988), Kazinczi, Beres & Narwal (2001), Burda & Oleszek (2004), Pilipavicius (2008) and Shafagh-Kalvanag et al. (2008). Glinwood et al. (2004) exposed barley plants to Cirsium arvense volatiles for 5 days and found a reduced attraction to aphids, though exposure to root exudates showed no effects.

VII. Phenology

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

Growth begins in spring after winter dormancy as the soil temperature begins to rise. In Montana, USA, shoot emergence began when mean weekly air temperatures were 5 °C or higher and was greatest at 8 °C or above. Dates of first emergence differed by up to 10 days between clones (Hodgson 1964, quoted by Moore 1975). Emergence was followed by rosette expansion, then rapid shoot growth 3 weeks later, with the most rapid vertical growth (mean 3 cm day−1) in the last 2 weeks of June. Donald (2000) developed a model for the date of shoot emergence based on degree-days of daily mean temperatures (°C) from 1 April. The model predicted 1% shoot emergence at 197 degree-days and c. 80% emergence at 587 degree-days, and provided a guidance window within which farmers should expect to apply weed control measures on cultivated ground.

In the UK the first signs of emerging shoots occur in late March to early April, followed by a developing rosette of leaves and elongation of the stem as air temperatures rise. The stems terminate in apical and axillary inflorescences from mid-June to July. The flower buds open in cymose order from the top of the plant to progressively lower order axillary branch capitula. The main flowering period is in early to mid-July with a conspicuous emergence of the pappus during late July to August. Bud production and flowering continue on the lowest order branches, and on later developed plants, previously cut or damaged, well into autumn (September to November). In North America higher summer temperatures may concertina flowering and seeding. Late summer and autumn winds facilitate dispersal of the pappus on dry days, though the achenes remain sessile in the capitula. From late September there is a gradual senescence and withering of the mature stem from the top downwards ultimately in early winter leading to death and usual disappearance of the above-ground shoots until the spring. Young rosettes can develop in late September to October at patch edges, within thin stands or where plants were cut or treated with herbicide during the summer. These continue to grow vegetatively in mild spells, albeit with diminished size, vigour and greenness, until killed by frost. Stems that flowered have usually senesced by this time (Wilson, Martin & Kachman 2006). It is uncertain to what extent the photoperiodic stimulus is translocated through the roots from old to these late developing young shoots. In Australasia there is a similar die-back and drying of aerial plant parts in the winter season. Detmers (1927) stated that some late shoots and late-germinated seedlings could survive in favourable winters in Ohio, USA.

VIII. Floral and seed characters

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

(A) Floral biology

The florets of C. arvense are borne on a common receptacle within an enveloping involucre of bracts forming a floral head or capitulum, typical of the Asteraceae. The angle of divergence is 21/55 (Lund & Rostrup 1901). The florets mature centripetally from the outside of the receptacle inwards, as also does subsequent seed set (Hayden 1934; Chancellor 1970). All the flowers in a capitulum may open in one day, especially in warm weather. The dioecious plants and clones produce either pistillate or staminate heads, which are readily distinguished (Hodgson 1968; Lloyd & Myall 1976). Pistillate (female) heads are flask shaped at anthesis with a compact crown of open, strongly odoriferous florets with a smell like Puccinia rust. Closer examination reveals relatively short corolla lobes, emergent styles and abortive dark coloured anthers without pollen. Mature female florets are soon displaced by a conspicuous emergent pappus, resulting in the typical grey/white voluminous fluffy seed heads (Fig. 9).

image

Figure 9.  Flowering and mature capitula of female and male plants of Cirsium arvense; the left-hand head of each pair represents mid-anthesis, and the right-hand head represents the maturing stage. (a) Female; left-hand mature capitulum with conspicuous emerging head pappus tuft; (b) male; left-hand mature capitulum bearing declined senescent florets and no pappus tuft visible.

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Staminate (male) heads are broader with a more rectangular base and an unkempt appearance when open, due to more elongate corolla lobes and longer (6.5 mm) pale pink anthers with abundant pollen attached to the styles though the stigmata remain unopened. The scent produced is vanilla-like and much stronger than from female flowers. Mature male heads become deflexed with withered dark brown florets and a barely visible less developed pappus (Fig. 9). Lloyd & Myall (1976) recorded quantitative differences between male and female heads. Male florets and their corolla lobes, styles and anther lobes were all significantly longer than female florets. Kay (1985) found the greater corolla lobe length (male 4.88 mm, female 2.81 mm), breadth (0.57, 0.36 mm) and anther length (4.46, 1.61 mm) on male florets to be reliable differences between the sexes. However, differences in capitula and fruiting pappuses were less reliable where hermaphrodite or sub-hermaphrodite male clones set seed. Female heads are narrow towards the tip before flowering but have broader bases than male heads. Female involucres increase in length and in width at the base after flowering, to support the elongated pappus and swelling achenes. Male involucres do not appreciably increase in length or basal width and the pappus does not lengthen so that the corollas remain visible. In fact, the involucre width constricts below the corollas so that maturing male heads become flask shaped. Data given by Kay (1985) and by Moore & Frankton (1974) for pappus lengths are: male, 11–14 mm in flower and fruit; female, 14 mm in flower, 20–30 mm in fruit. The vestigial anthers in female flowers produce no pollen. In male flowers each anther contains 500–800 pollen grains, with means totalling 3530 (Kay 1985) to 3800 (Lloyd & Myall 1976) grains per flower.

The stamen filaments contain broad and extensible cells which allow contraction to half the filament length before and after flowering or in response to a stimulus. Each anther bears a sterile appendage at its tip and base, creating a tube in the male flowers. An abrupt, forceful lengthening of the style past the upper appendage, concurrently with a contraction of the stamen filaments, effects a sweeping of pollen from the anthers by a collar of pointed unicellular hairs at the base of the stigma (Fig. 10; Müller 1883). After emergence of the style in female flowers the branches of the stigma widen to expose the dorsal surfaces. These are clothed with unicellular papillae, on which the pollen grains adhere. The lower part of the floral tube includes five cavities or flattened cells which are involved in the strong curvature, more pronounced in the male, of the florets towards the perimeter of the capitulum as they mature (Lund & Rostrup 1901).

image

Figure 10.  Florets of Cirsium arvense at anthesis: (a) female with empty, dark coloured anthers, elongating pappus and open stigma; (b) male with shorter pappus and stigma bearing pollen mass swept out from anthers by emergent style.

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The pollen of Cirsium arvense is very similar to that of all other British Cirsium species (De Vere 2007). The grain is roughly spherical (circular under the microscope) with both polar and equatorial diameters c. 42–48 μm when mounted in glycerol jelly. It is trizonocolporate, i.e. it has three colpi (furrows) and three pori (pores) arranged around the equator of the grain. The long axis of each colpus extends from pole to pole, is relatively short and narrow with attenuate ends, and can be seen in its entirety in an equatorial view. Each porus is more or less circular or slightly elongate meridionally, and is wider than and located centrally on each colpus. The external wall of the pollen grain is echinate with 4–5 μm echinae spaced equidistantly over the surface of the grain. Each echina is without a basal constriction and often has an internal cavity. The exine consists of two layers of rod-like structures: the innermost true columellae and the outer baculae. Between the bases of the echinae the columellae are arranged uniformly and radially; those beneath the echinae are longer and obliquely orientated towards the centre of the echina base. The baculae are finer and shorter than the columellae and are arranged uniformly in a continuous layer, including under the echinae bases (P. Wiltshire and J. Webb, pers. comm.).

Pollination in C. arvense was described by Knuth (1908) and Müller (1883). The narrow floral tube widens to a bell-shaped throat, 1–1.5 mm, bearing five linear-divergent corolla segments 4–5 mm. Nectar rises up the corolla tube to the throat of the floret, making it accessible to a wide range of insects (Table 2) with either a short or long proboscis. The lengthening style pushes up a pollen mass to the tip of the anthers and on to the top of the style. The surface-protruding echinae and slight stickiness of the pollen grains lead to their agglomeration and ready adherence to the hairs of visiting insects and also to the receptive papillae of the stigma. The two branches of the style bend outwards at their edges and may also open at the upper end, allowing deposition of pollen onto the numerous receptive papillae.

Lund & Rostrup (1901) describe two different forms of pollen grain: large (0.052 mm) diameter, colourless, with 13–15 conical points (echinae) and a shiny profile; and smaller (0.042 mm) diameter, yellow, with a profile of 30–40 very fine points and containing an oily liquid which occasionally oozes small droplets on the surface of the grain. The smaller grains contribute to the stickiness of the pollen mass adhering readily to the stigma and to insects.

(B) Hybrids

Two hybrids of C. arvense have been recorded as casuals in the British Isles (Stace 1997; Sell & Murrell 2006): C. × boulayi E. G. Camus = C. acaule × C. arvense, with intermediate capitulum and pubescence characters; C. celakovskianum Knaf = C. palustre × C. arvense, with winged stems below and intermediate decurrent, sinuate-lobed leaves, capitula and corollas. According to Moore (1975), approximately nine hybrids between C. arvense and old world Cirsium spp. were reported by Hegi (1929). A possible hybrid with C. hookerianum Nutt, native to British Columbia, was described as a rarity by Moore & Frankton (1965). Detmers (1927) referred to several hybrids of C. arvense, e.g. with C. palustre, C. erisithales, C. flavispinum Boiss., C. heterophyllum and C. acaule.

(C) Seed production and dispersal

A single anatropic ovule develops in the ovary and ultimately completely fills the achene, with the radicle directed downwards. After fertilization, the walls of the epidermal cells thicken greatly whereas the inner cells of the ovary swell enormously and their walls become sclerified with a shiny white material (Fig. 11). In the centre of the capitulum the achenes are straight but towards the periphery they become more and more curved. Only approximately half of the total capitula and only a small number of achenes mature (Lund & Rostrup 1901).

image

Figure 11.  Transverse section through the wall of a mature achene of Cirsium arvense, showing enlarged and sclerified cells. After Lund and Rostrup (1901), with permission of the Royal Danish Academy of Sciences and Letters.

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The florets of thistle are structurally hermaphrodite but functionally either male or female, though male plants occasionally produce ripe fruits. No female flowers have been observed to produce pollen (Detmers 1927). Bakker (1960) did not find fruits on male plants on the polders. Kay (1985) placed male flowers, morphologically distinct from females by corolla-lobe length and breadth and anther length (see above), into three groups of male-flowered clones (‘males’):

  • 1
     typical males with low seed-set
  • 2
     hermaphrodites with high seed-set, > 10 seeds set per capitulum and
  • 3
     sub-hermaphrodites with an intermediate seed set of 2–10 seeds per capitulum.

Mean numbers of seeds set per head were: females 50.6 (range 13.8–97.5) hermaphrodites 36.1 (13.6–64.7); sub-hermaphrodites 6.2 (2.8–9.8); and low seed-set males 0.82 (0.36–1.16). Seed sizes and masses were variable on both male and female clones but not significantly different. Data for male and female respectively were: mean lengths: 3.03 and 2.98 mm; widths 1.15 and 1.08 mm; masses 1.33 and 1.44 mg. Lloyd & Myall (1976) recorded 79 seeds set per female head, 2.9 per male, with mean lengths 2.94 and 2.55 mm and mean masses 0.95 and 0.50 mg per seed respectively. Stevens (1932) recorded a mean of 1.575 mg per seed and a count of 680 seeds produced by one flowering stem though many were immature. Hodgson (1964) found considerable variation of seed size among clones, with a mean of 0.96 mg (range 0.7–1.5 mg) per seed. Bostock (1978) quoted 1.820 ± 0.107 mg per seed, 37% of which was embryo, 24% pericarp and 39% pappus.

Donald (1994a) tabulated records of the fecundity of C. arvense from several countries indicating wide limits of variation. A vigorous shoot may carry up to 100 flowering heads in a season (Detmers 1927; Bostock & Benton 1979). Bakker (1960) observed 32–69 heads per shoot in favourable conditions. Lund & Rostrup (1901) recorded up to a maximum of 690 capitula on one female shoot though among many shoots a mean of only 80 attained flowering, produced on up to the fourth order of branching. Mean numbers of florets per capitulum were 120 for female and 110 for male. Male plants produced many fewer capitula but most of these flowered. In Australia, Amor & Harris (1974) recorded 100–4900 well-developed seeds per shoot. Seed numbers per head depend on the degree of pollination. Hayden (1934) found 98, Derscheid & Schultz (1960) up to 83 and Bakker (1960) 0–98. In Montana, Hay (1937, cited by Moore 1975) recorded an average of 1530 seeds per shoot, with a maximum of 5300. Lalonde & Roitberg (1994) reported significantly higher achene mass in plants setting fewer seeds resulting from pollen limitation, though proportions of aborted seed were not affected. Primary sex ratio was also unaffected by the availability of pollen: highly female-biased ratios occurred in both high- and low-pollen availability treatments. Competition especially for light could reduce seed output (Bakker 1960).

Field inspection of maturing capitula confirms the erratic variation in achene development and quality within the involucre. Deviations from the normal grey-brown straw colour and bold shiny seed coats are apparent as thin and physically damaged seeds or seeds with pale and hyaline seed coats (Gill 1938). He found very few seeds were produced on plants cut down when flowering and, though the achenes appeared externally normal, they were lacking fully developed embryos and were incapable of germination. Forsyth & Watson (1985) and Lalonde & Roitberg (1992a) reported extensive physical damage to capitula and seeds in Canada. Heimann & Cussans (1996) believed that poor seed yield, with many shrivelled achenes per head or poor fill of endosperm, could be a result of poor pollination or possibly genetic factors, though viable seed could mature from 8 to 10 days after flowering. Post-dispersal damage to the seeds could be extensive, with 55–88% predation recorded in the Netherlands (Van Leeuwen 1987, cited by Heimann & Cussans 1996). Seed predation was a major pre-dispersal reason for low seed output with Dasineura gibsoni Felt. and Orellia ruficauda (F.) the main insects (see IX A). Increased seed sterility of C. arvense resulting from abortion of young seeds and degeneration of the embryo and/or the endosperm were observed by Czapik, Izmailow & Koscinska-Pajak (2002) on polluted wastes in Poland. These included copper mine waste, power station fly ash and soda factory waste. Post-dispersal seed removal in cereal fields in the UK was mainly by birds in spring and other animals later in the year (Holmes & Froud-Williams 2005). Larson et al. (2005) found the impact of thistle feeding insects on the potential for C. arvense to spread by seed (seed production, germination and viability) to be negligible in a South Dakota wildlife reserve.

Seed dispersal

The plume or pappus in C. arvense florets is composed of some 70 rays arranged in bundles of 3–4 in spiral order on the floral tube. In the male it does not lengthen appreciably after fertilization whereas in the female it elongates to about double the length of the corolla to 24–30 mm. Towards the base of the plume, hygroscopic tissue holds the rays erect in damp weather. In dry conditions the rays bend outwards tending to lift the plume and achene from the receptacle. The rays bear fine hair-like laterals of about 2 mm (modified unicellular epidermal cells) which contribute to the lightness of the plume (Lund & Rostrup 1901).

Early reports (Detmers 1927) and popular perception assumed that C. arvense seeds become widely dispersed with the plumed thistledown blown by the wind. Closer observation (Bakker 1960; Chancellor 1970) showed that the achenes were firmly attached to the receptacle whereas the pappus was very easily detached (Moore 1975). Bakker collected several thousands of plumes blown by wind of velocity 6–8 m s−1 into a pasture free of fruiting thistles. At distances of 10 m, 1 km and 2 km from the seed source proportions of plumes with attached achenes were 9.9%, 0.2% and 0% respectively. Non-viable achenes were attached to the receptacle indefinitely, and Bakker concluded that creeping thistle was not well adapted to anemochorous dispersal. However, he thought the initial introduction onto the drained polders had been by wind but the seeds could have landed on the waters before drainage. The majority of ripe achenes therefore reach the ground locally through gravity or decay of the parent plant. In damp overcast conditions and in high humidities the involucre remains closed; drier and breezy atmospheres are required for release of the pappus. Bostock & Benton (1979) observed that some fruiting capitula do not open sufficiently in late summer for dispersal. Wallace et al. (2005) found the highest numbers of seeds were dispersed at the edges of thistle patches and an exponential decline in numbers as distance from the patches increased. This pattern was however affected by landscape features such as gullies or local objects, creating turbulence which could increase or curtail dispersal affect the distances any wind-borne seed are transported (Heimann & Cussans 1996). Thus trees upwind resulted in more seeds being dispersed away from a patch. The studies of Fresnillo & Ehlers (2008) in Denmark showed a significant reduction in dispersibility of achenes on islands compared with the mainland, and also detected significant differences within populations, suggesting a genetic component. There was in addition a positive correlation between drop time of diaspores and the quotient mass of diaspore/size of pappus.

While the efficiency of wind seed dispersal may be very low, it has the potential for introduction to new sites and to maintain genetic diversity. Wind dispersal was believed to have greatly aided the extensive and rapid spread of C. arvense in North America (Hayden 1934). Human activities, particularly agricultural, are thought to have been the major influence in its global and local spread. Intercontinental introduction was mainly through contamination of crop seed, livestock feeds, hay and bedding (Detmers 1927; X). On a more local scale these mechanisms would explain the spread of thistle along rail and road routes, near grain elevators and feed factories. In North America ducks and waterfowl were suspected of carrying seed but no evidence could be found. After feeding C. arvense seeds to Mallard ducks, examination of the alimentary canals showed achenes present in the crops but these became ground up in the gizzard and no whole seeds reached the intestines or the excreta (Hayden 1934). Finches feed on thistle seeds which are macerated by their bills (Detmers 1927). Seeds can be carried on clothing and on the skins of animals. Soil transport is common by animals such as cattle, moles, rats, on the hooves of horses or attached to tractors and implements and during cultivations. Dispersal in goat droppings was recorded by Beskow, Harrington & Hodgson (2008). The presence of elaiosomes, oil-bearing appendages, inside the collar-like distal ends of the achenes, was considered by Pemberton & Irving (1990) to be associated with dispersal by ants (myrmecochory), which could enhance weediness in established stands or assist colonization in new and relatively closed areas. Irrigation and drainage waters have been found to transport thistle seeds (Wilson 1980), with potential for travelling long distances (Hayden 1934).

(D) Viability of seeds, germination

Secondary dormancy is induced in seeds buried in the soil or immersed in water. Longevity of the seeds has been found to increase with depth of burial in the soil. In the Duvel long-term experiment (Toole & Brown 1946) germination percentages were higher after burial at a depth of 105 and 55 cm than at 20 cm and viability was retained for up to 21 years. Bakker (1960) found seeds buried at 40 cm were still viable after 2.5 or 4 years, in contrast with seeds at 1 cm depth, and that seeds immersed under water were still viable after 2.5 years. Bruns & Rasmussen (1957) had earlier found that seeds immersed in water retained viability: germination increased up to 4 months then steadily declined to zero after 54 months of immersion. Rates of germination fell during the warm summer period but recovered again as the water cooled. Comparing burial of seed at 5–10 and 15–20 cm soil depths, Van Leeuwen (1987, cited by Moore 1975) found three to five times more residual viability at the greater depth after 2 years. Hodgson (1964) recorded viability differences between clones. Germination of fresh seed and response to dormancy-breaking agents were also found by Williams (1966) to vary with clone. Germination decreases in seeds stored dry at room temperatures (Donald 1994a). Storage in wet sand during winter stratified seeds more strongly, resulting in better germination in spring than storage in dry sand (Kolk 1962, cited by Håkansson 2003). Seeds died when stored at 27 °C (Bostock & Benton 1979). Few seeds germinate after passage through a horse (Lund & Rostrup 1901). Viability is also largely lost after ingestion by cattle; only 0.5% thistle seeds fed to a cow germinated but this viability was maintained after storage in faeces for 3 months at both 5 and 20 °C (Lhotska & Holub 1989). However, 5% of the seeds remained viable after passage through goats (Beskow, Harrington & Hodgson 2008).

Though seeds of C. arvense are able to germinate immediately after dispersal (Hayden 1934; Bakker 1960; Hodgson 1968; Hoefer 1981; Heimann & Cussans 1996), it has been generally found that germination increases following a period of after-ripening. Bakker (1960) recorded c. 14% germination immediately after harvest, but 3–6 months later almost all seeds could germinate if placed in conditions conducive to germination. This length of after-ripening coincides with lowered overwintering temperatures which effectively prevent premature germination. Autumn (‘fall’)-germinated seedlings are unable to develop sufficient storage roots to survive the winter. Bostock & Benton (1979) found fresh seed had the lowest germination/deepest dormancy and that germination rates were faster in stored seed, indicating a loss of dormancy. Mean time to germination fell from 9.4 to 6.4 days after 3 months of storage at 3 °C.

The main factors affecting germination are temperature, light and moisture. Bakker (1960) found maximum germination at 30 °C and with strongly intermittent temperatures (10–28 °C). Other workers have reported 30 °C as optimal. Temperatures found best for germination by Wilson (1979) were: 30 °C for 24 h; 20 °C for 16 h + 30 °C for 8 h; 30 °C for 16 h + 40 °C for 8 h. Amor & Harris (1974) found alternating 12 h at 15 °C with 40 °C reduced germination; pre-chilling increased germination at a constant 20 °C. Kumar & Irvine (1971) found pre-chilling an advantage but not essential in light, especially when germinated at 30 °C. Chilling fresh seed at 4 °C for 10 days significantly increased germination with an additional increase after further chilling (Bostock & Benton 1979); a period of after-ripening was necessary before chilling became effective. Seed recovered from the soil also responded to chilling. Cooling by evaporation from inundated soil was thought to prevent germination during normal summer temperatures (Lund & Rostrup 1901).

Light increases germination but rates are higher in alternate light and dark compared with continuous light or continuous dark, though differences were not significant at 30 °C (Kumar & Irvine 1971; Wilson 1979). Similarly, germination in a 17-h photoperiod was significantly greater than in continuous light or continuous dark (Bostock & Benton 1979). Wilson (1979) found that gibberellic acid overcame the light requirement for germination and that exposure to 8 h photoperiods increased germination compared with continual darkness. Kolk (1962, cited by Håkansson 2003) found that young seeds germinated well in bright daylight and older seeds better in weak light. Bakker (1960) found that seedlings die below 20% full summer light, are retarded even at 60–70% levels and did not survive in dense crops. Seeds sown into an existing pasture did not germinate whether grazing was continuous or rotational (Edwards, Hay & Brock 2005), confirming earlier work (Edwards, Bourdôt & Crawley 2000) where ungrazed vegetation reduced seedling recruitment. Shading with winter wheat or artificial shading reduced germination compared with control (Dau et al. 2004). Removal of the wheat and shading cloths in August resulted in secondary germination in the shaded treatments to give equal seedling numbers in all treatments. Shading reduced the number of root buds and the biomass of both shoots and roots. Simulating moisture stress with solutions of mannitol, they reported a gradual reduction in germination with water potentials of −0.1 to−0.5 MPa, a significant decline at −0.7 Mpa followed by a rapid decline to −1.5 MPa. Saturated soils with poor aeration reduce germination (Bakker 1960) but some germination may be possible at very low soil moisture contents (Bostock 1978; Wilson 1979). However, Wilson found seedlings did not survive average water potentials below −0.17 MPa, and Bakker (1960) that seedlings did not tolerate drought stress. On wetlands in Colorado and Wyoming, Laubhan & Shaffer (2006) recorded germination of 68% with a combination of shallow (1 cm) burial and wet conditions compared with 0.3% at a deeper (2–3 cm) seed burial in saturated soils. Kollar (1968, cited by Håkansson 2003) also found that burying the seed by as little as 1.5 cm could inhibit germination. Optimum depth for emergence was 0.5–1.5 cm, though germination can occur on the soil surface or from depths up to 5–6 cm (Bakker 1960; Wilson 1979). Lund & Rostrup (1901) found that the speed of germination varied with depth of seed in the soil, ranging from 8 to 9 days when sown at 0–5 mm to 13–18 days sown at 50 mm. Seeds sown at 80 mm did not germinate but germinated after 10 days if dug up after 2 months and resown at 5 mm. Adams (1994) found that seed diameter did not affect percentage germination but was related to an increase in shoot dry weight after 8 months, indicating a direction in early development to maximum shoot growth.

Sodium chloride solutions stronger than 5000 ppm reduced seed germination which however was still possible at 20 000 ppm (Wilson 1979), in accord with Reed & Hughes (1970) who found C. arvense in soils with up to 2% salt. The optimum pH for seed germination was found (Wilson 1979) to be between 5.8 and 7.0, rates declining sharply above and below these values. Cirsium arvense is not well represented in the seed banks of arable fields even where it is dominant as a weed (Hill, Patriquin & Vander Kloet 1989). This is because most seeds germinate within 1 year of dispersal either at or near the soil surface or if buried after soil mixing by cultivations (Roberts & Chancellor 1979). However, Thompson, Bakker & Bekker (1997) considered the thistle seedbank to be extensive with densities up to 1200 m−2.

(E) Seedling morphology

Germination is epigeal and seedling morphology is similar to many members of the Asteraceae. The radicle emerges from the distal end of the achene and elongation of the hypocotyl raises the cotyledons above-ground. The cotyledons may be erect or bent over, at length withdrawing from the seed coat and achene. Initially adpressed the oval-elongate-ovate cotyledons open to expose a frosty-puberulent upper surface with minute hairs (Hayden 1934; Fig. 12). Further expansion and greening take place before signs of the first leaf appear in the deep cleft between the cotyledons. The first foliage leaves are ovate-rounded, soft and bear regularly spaced coarse marginal hairs and very short surface bloom. Later leaves are stiffer, more lanceolate with a serrate and undulate lobed edge bearing a terminal and many marginal spines.

image

Figure 12.  Stages in the germination of Cirsium arvense: (a) seeds with emergent radicles, 1 week; (b) seedling after emergence with bent hypocotyl, 2 weeks; (c) cotyledons open and hypocotyl elongating, 4 weeks; (d) seedling with first true leaves, 6 weeks; (e) developing rosette and root elongation prior to branching, 10 weeks.

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The hypocotyl is of varying length depending on the depth of the germinating seed. The simple primary root, of smaller girth than the hypocotyl, soon develops side branches and lengths of darkened absorbing surface. There is a short time between the seedling stage and the onset of perennation, requiring close monitoring of control treatments applied to seedlings (Bayer 2000); bud development can begin on the roots after 19 days (Wilson 1979).

IX. Herbivory and disease

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

(A) Animal feeders or parasites

The insect fauna of C. arvense was reviewed by Redfern (1983), who noted that this species supported a rich and varied fauna of insect herbivores with associated predators, parasites and inquilines (species inhabiting the same location and using the food of another species). Some insects are monophagous but several occur on other Asteraceae species. The most important species affecting the thistle plant are flower visitors (Table 2), gall-forming insects, e.g. Urophora cardui, under study for possible biological control (see XI), aphids and seed predators. A full UK list of phytophagous species from the Biological Records Centre Database (Biological Records Centre 2009) together with the plant parts affected is given in Table 4. Insects recorded in Europe by Zwolfer (1963) include 17 species endophytic and four species occurring externally on the flower heads and buds, 15 endophytic in the stem, six endophytic in the leaves; 45 occurring externally on the stem, roots and leaves and 52 occasional visitors. Surveys of insects on C. arvense have also been made in Europe by Winiarska (1986) and Freese (1994), in Canada by Maw (1976) and in Montana, USA, by Story, Desmet-Moens & Morrill (1985). Forsyth & Watson (1985) found 20–85% of heads were attacked by Orellia ruficauda (F.), producing up to two pink larvae per head. The adult oviposits into the developing flower heads preferentially 1 day before opening. Larval mass and reproductive success are reduced if eggs are laid at other stages of development. After egg-laying the flies place a circle of fluid around the rim of the head signalling rejection by flies arriving later (Lalonde & Roitberg 1992b). The larvae, up to 3–7 per head, bore through the pericarp and endosperm without affecting the seed coat except at the exit hole and later form cocoons from the pappus within the head. In British Columbia 5–8% of heads were affected; in Europe, 0.4–26% (Heimann & Cussans 1996). The young achenes could be pierced and sucked by Dasineura gibsoni Felt (Detmers 1927).

Table 4.   Insect species recorded from Cirsium arvense
Group, family and speciesPlant part affectedNotesSource
Acari
Eriophyidae
 Aceria anthocoptes (Nalepa)Leaves forming gallsPotential for biological control1, 3
 Vasates leontodontis (Lindroth)LeavesMite1
Coleoptera
Chrysomelidae
 Cassida rubiginosa Müller,O. F  1, 3
 Lema cyanella (L.) Larvae, adult1, 3
 Longitarsus luridus (Scop.)Leaves, miningLarvae, adult1
 Psylliodes chalcomera (Illiger) Adult1
 Sphaeroderma rubidum (Graelis)LeavesLarvae, adult, mining1
 S. testaceum (F.)LeavesLarvae, adult, mining1
Curculionidae
 Ceutorhynchidius horridus (Panzer)StemAdult, mining1
 Cleonus piger (Scop.)Stem, forming galls, principal hostBiological control1, 2, 3
 Hadroplantus litura (F.)Stem, principal hostAdult mining; biological control1, 2, 3
 Larinus planus (F.)FlowersBiological control1, 2, 3
 Lixus algirus (L.) Larvae, adult1
 L. elongatus (Goeze) Adult1
 Otiorhynchus auropunctatus GyllenhalMiningAdult1
 Rhinocyllus conicus (Froelich)FlowersLarvae, adults; biological control1, 2, 3
 Stenocarus umbrinus (Gyllenhal) Adult1
 Tanymecus palliatus (F.) Adult1
Mordellidae
 Mordellistena pumila (Gyllenhal) Larvae1
Diptera
Anthomyiidae
 Pegomya steini Hendel Larvae1
Agromyzidae
 Melanagromyza aeneoventris (Fallén)StemLarvae1, 2
 Phytomyza autumnalis GriffithsLeaves, mining; principal hostLarvae1, 2
 P. cirsii Hendel LeavesLarvae1, 2
 P. horticola GoureauLeaves, miningLarvae1
 P. spinaciae HendelLeaves, miningLarvae1, 2
Cecidomyidae
 Clinodiplosis cilicrus KiefferMiningLarvae1
 Dasineura cirsii (Rubsaamen) Gall midge, larvae1
 D. gibsoni Felt  Gall midge, larvae1
 Jaapiella cirsiicola (Rubsaamen)MiningLarvae1
 J. compositarum (Kieffer) Larvae1
Tephritidae
 Euleia heracleii (L.)MiningLarvae1
 Orellia ruficauda (F.) Larvae1, 3
 Paroxyna lhommei Hering Adult1
 Tephritis comata (Loew) Larvae1
 Terellia ruficauda (F.) Larvae1
 Urophora cardui (L.) Larvae1, 3
 Xyphosia miliaria (Schrank) Larvae1, 3
Hemiptera
Aphididae
 Aphis fabae Scopoli IILeaves, stem and flowersLeaf rolling, larvae, adult1, 2
 Brachycaudus cardui (L.) IILeaves, stem and flowersLarvae, adults1, 2
 Capitophorus elaeagni (del Guercio) IILeaves, miningPest1, 2
 C. hornii (Börner, C.) Monophagous1, 2
 Dactynotus aeneus Hille Ris LambersStem, leaves 1, 2
 D. cirsii (L.)Leaves, stem, and flowersMonophagous1, 2
 Dysaphis lappae (Koch, C. L.)StemAttended by ants1, 2
Cicadellidae
 Eupteryx notata CurtisLeaves, miningLimestone areas1, 2
Lachnidae
 Protrama flavescens (Koch, C. L.) Attended by ants1
 P. radicis (Kaltenbach)RootsAttended by ants1, 2
Miridae
 Lygocoris pabulinus (L.)  1
 L. spinolai (Meyer-Dur)  1
Hymenoptera
Apionidae
 Apion carduorum Kirby, W. Larvae, adult1
 A. lacertense TottenhamStemPrincipal host2
 A. onopordi Kirby, W Adult1
Lepidoptera
Coleophoridae
 Coleophora follicularis (Vallot)Leaves and stem, miningLarvae1
 C. paripenella ZellerLeaves,miningLarvae1, 2
 C. peribenanderi TollLeaves, miningLarvae, under leaves1, 2
Gelichiidae
 Scrobipalpa acuminatella (Sircom)Leaves, mining 2
Nymphalidae
 Cynthia cardui L. Larvae1
Oecophoridae
 Agonopterix arenella (Denis & Schiffermüller)Leaves 2
 A. carduella (Hübner)Leaves 2
 A. propinquella TreitschkeLeaves, mining 2
 A. subpropinquella StaintonLeaves 2
Pyralidae
 Mutuuraia perlucidalis (Hübner)LeavesMonophagous2
 Sitochroa verticalis (L.) Migrant; larvae1
Tortricidae
 Aethes cnicana (Westwood)Stem,fruitsMonophagous2
 Cnephasia asseclana (Denis & Schiffermüller)Leaves, stem, miningLarvae, webbing1
 C. incertana TreitschkeLeaves, stem, miningLarvae, webbing1
 C. stephensiana (Doubleday)Leaves, stem, miningLarvae, webbing1
 Epiblema scutulana (Denis & Schiffermüller)Stem, rootsMonophagous2
 Lobesia abscisana (Doubleday)Shoots, stemLarvae, webbing, monophagous1, 2
Thysanoptera
Thripidae
 Thrips angusticeps Uzel Larvae, adult1
 T. vulgatissimus HalidayFlowersLarvae, adult, gregarious1
Tingidae
 Tingis ampliata (Herrich-Schaffer)Leaves, stem, rootsLarvae, adult, gregarious, biological control1, 3
 T. cardui (L.)  1

The eelworms: Pratylenchus penetrans (Cobb) Chitwood & Oteifa, Ditylenchus dipsaci (Kuhn) Filipjev, Meloidogyna incognita var. acrita (Kofoid & White) Chitwood and M. hapla Chitwood have been recorded in North America (Watson & Shorthouse 1979; Donald 1994a). Bezemer et al. (2004) found greater eelworm numbers, mainly Paratylenchus spp., in high species diversity plots. In glasshouse studies, Belair et al. (2007) found thistle to be a very good host for Pratylenchus penetrans, with high multiplication rates. Thistle leaves are reported to be palatable to the snail: Cepaea nemoralis L. (Grime, MacPherson & Dearman 1968). Damage to the leaves by the mite Aceria anthocoptes (Nalepa) was described by Rancic, Branka & Petanovic (2006) in Serbia.

(B) Plant parasites

Thistle broomrape Orobanche reticulata is an endangered species parasitic on Cirsium and Carduus spp. It occurs very locally in a limited number of sites on magnesian limestone and chalk in Yorkshire, including riverside gravels, roadsides, waste places and grassland (Simpson 1993; M.B. Usher, pers. comm.). Dodder (Cuscuta sp.) has been reported in New York State (USDA 1960, quoted by Simpson 1993).

(C) Plant diseases

Table 5 lists species of fungi associated with C. arvense in the UK, including those causing disease; several of these are possible biological control organisms (see XI). Seedling damping-off organisms and rusts on the adult plant have the most significant effects on creeping thistle. The bacterium Pseudomonas syringae Van Hall has been reported in local abundance in south-east England, forming a conspicuous white deposit on creeping thistle shoots, visible from a distance (D. Streeter, pers. comm.). This species pv. tagetis Hellmers has been tested in North America as a biological control agent on C. arvense (Johnson, Wyse & Jones 1996; Tichich & Doll 2006) and genetically typed (Kong et al. 2004, 2005).

Table 5.   Microfungi recorded from Cirsium arvense in the British Isles
Phylum, order or familySpeciesPlant part (*pathogenic)Source
Ameobozoa
StemonitidaceaeComatricha tenerrima (Berk. & M. A. Curtis) G.ListerStems1
LiceidalesCribraria macrocarpa Schrad. 1
PhysariaceaePhysarum pusillum (Berk. & M.A. Curtis) G. ListerLeaves1
TrichialesArcyria cinerea (Bull.) Pers. 1
 Trichia scabra Rostaf*Leaves1
Oomycota
AlbuginalesAlbugo tragopogonis (DC.) Gray*Forms blisters on leaves and stem1, 2
PeronosporalesBremia lactucae Regel*Downy mildew1
Ascomycota
BotryosphaerialesPhyllosticta cirsii Desm.*On leaves4
CapnodialesPericoniella mucunae M. B. EllisDead leaves1
Ramularia cirsii Allesch.*Spots on fading leaves1, 2
R. didyma (Hartig) Wollenw.*Leaf spots1, 2
DiaporthalesDiaporthe arctii (Lasch) Nitschke*On old stems1, 2
D. pardalota (Mont.) Nitschke ex Fückel*On old stems1
Diplodina cirsii Grove*On dead stems4
Monodictys levis (Wiltshire) S. HughesDead stems1, 2
Phomopsis cirsii Grove*Dead stems and leaves; roots - endophyte1, 2, 4
Valsa ambiens (Pers.) Fr.Roots – endophyte1
ErisyphalesErisyphe convolvuli DC.*Leaf and stem mildew1, 2
E. mayorii S. Blumer*Leaf and stem mildew1
E. polygoni DC.*Leaf and stem mildew1
Golovinomyces cichoracearum DC. var. cichoracearum*Leaf and stem mildew1
HeliotalesBotrytis cinerea Pers.*Leaf, stem, flowers and fruits mildew1, 2
Calycina herbarum (Pers.) GrayDead stems1
Calycellina chlorinella (Ces.) DennisDead stems, common1, 2
Crocicreas coronatum (Bull.) S. E. CarpDead stems, common1, 2
Dasyscyphus grevillei (Berk.) MasseeDead stems, very common1, 2
Duebenia compta (Sacc.) Nannf. ex B. Hein*Leaf and stem mildew2
Hyalopeziza millepunctata (Lib.) Raitv.Dead stems1, 2
Hymenoscyphus epiphyllus (Pers.) Rehm*Leaf and stem mildew1, 4
H. repandus (W. Phillips) DennisDead stems and inflorescences1
H. pileatus (P. Karst.) KuntzeDead stems and leaves2
Lasiobelonium mollissimum (Lasch) SpoonerDead stems1
Mollisia cirsiicola GremmenDead stems1
M. clavata GremmenDead stems1
M. coerulans Quél.Dead stems2
Pezizella discreta (P. Karst.) Dennis*On stems1, 2, 3
Pglareosa Velen.Dead stems1, 2
Pirottaea brevipila (Roberge ex Desm.) Bond*Old stems1, 2, 3
P. rubrotinctum GraddonDead stems2
Pseudospiropes rouselianus (Mont.) M. B. EllisDead stems1, 2
Pyrenopeziza adenostylidis (Rehm.) Gremmen*On stems1, 2, 3
P. carduorum Rehm.Dead stems1, 2
P. clavata (Gremmen) Gremmen*On stems1, 2, 3
P. revincta (P. Karst.) GremmenDecaying stems1, 2
Sclerotinia sclerotiorum (Lib.) de BaryDead and decaying stems and leaves1, 2
Unguiculella eurotioides (P. Karst.) Nannf.Dead stems2
HypocrealesAcremoniella atra (Corda) Sacc.Dead stems, leaves and seeds2
Clonostachys rosea (Link) Schroers et al.Dead stems and leaves2
Fusariella hughesii Chab.-Frydm.Dead stems and leaves2
Gibberella avenacea R.J. Cook*On leaves1
Glomerella cingulata (Stoneman) Spauld. & SchenkDead stems and leaves2
Hypocrea gelatinosa (Tode) Fr.*On leaves1
Verticillium albo-atrum Reinke & Berthold*Shoots wilt2
Volutella ciliata (Alb. & Schwein.) Fr.Dead plants; very common2
MicroascalesCephalotrichum microsporum (Sacc.) P. M. KirkDead stems1, 2
C. stemonitis (Pers.) Nees.Dead stems1, 2
MycosphaerellalesCladosporium cladosporioides (Fresen.) de VriesDamaged plants; common2
C. herbarum (Pers.) LinkDead plants; very common2
C. macrocarpum PreussDead plants; common2
C. sphaerospermum Penz.Dead plants; common2
Mycosphaerella tulasnei (Jancz.) LindauDead plants2
OnygenalesOidodendron tenuissimum (Peck) S. HughesDead plants2
OrbilialesArthrobotrys oligospora Fresen.Dead plants; cobwebby2
OstropalesCryptodiscus rhopdoides Sacc.Dead stems2
PleosporalesAlternaria alternata (Fr.) Kiessl.*Causes shoot necrosis and occurs on dead plants1, 2
Dendryphion comosum Wallr.*Hyphomycete1, 3
D. nanum (Nees) S. HughesCommon on dead stems1, 2
Endophragmia hyalosperma (Corda) Morgan-Jones & A.L.J. ColeDead stems; common2
Epicoccum nigrum LinkVery common on damaged plants1
Leptoshaeria doliolum (Pers.) Ces. & De Not.*Very common on dead stems1, 2
L. macrospora (Fückel) Thümen*Dead stems1, 2
L. purpurea Rehm*Dead stems1, 2
L. rubella Sacc. & Malbr.Dead stems; very common2
Lophiostoma vagabundum Sacc.*On stems1, 3
Nodulosphaeria cirsii (P. Karst.) L. Holm*On old stems4
Ophiobolus acuminatus (Sowerby) Duby*On stems3
O. cirsii (P. Karst.) Sacc.Dead stems1, 2
Periconia byssoides Pers.On leaf spots and damaged stems;very common2
P. cookei E. W. Mason & M. B. EllisDead stems; very common2
P. minutissima CordaDead stems and leaves; common2
Phaeospheria vagans (Niessl.) O. E. Erikss.*On stems1
Phoma cirsii Dietel & P. Syd.*On dead stems4
Phoma grovei Berl. & Voglino*On dead stems4
P. herbarum Sacc.Dead stems; common1, 3
Phoma rubella GroveDead stems1, 2, 3
Pithomyces chartarum (Berk. & Curt.) M. B. EllisOn leaves; causes facial eczema in grazing livestock1
Pleospora herbarum (Pers.) Rabenh. ex Ces. & De Not.Produces spots on leaves and stems1
Urocladium atrum PreussDead plants; antagonist of Botrytis cinerea2
U. chartarum (Preuss) E. G. SimmonsDead plants2
SordarialesChaetomium piluliferum J. DanielsDead plants2
Incertae sedisSphaeronema floccosum GroveDead stems4
Xylohypha nigrescens (Pers.) E. W. MasonDead leaves; endophyte1
Basidiomycota
AgaricalesCalyptella capula (Holmsk.) Quél.Dead stems1
Collybia confluens (Pers.) P.Kumm.On leaves1
Coprinopsis atramentaria (Bull.) RedheadDead stems and leaves1
Cortinarius helvelloides (Bull.) Fr.Dead leaves1
Cyathus olla (Batsch) Pers.On leaves1
Flagelloscypha minutissima (Burt) DonkDead stems1
Lycoperdon molle Pers.On leaves1
Melanoleuca melaleuca (Pers.) MurrillDead stems1
BoletalesBoletus erythropus (Fries) KrombholzOn leaves1
DacrymycetalesCalocera pallidospathulata D. A. Reid*On leaves1
EntylomatalesEntyloma ficariae (Cornu & Rose) Fisher V. Wald*Causes leaf spot1
UredinalesPuccinia calcitrapae DC.*Causes rust on leaves and shoots1
P. caricina DC.*Causes rust on leaves and shoots1
P.cnici H. Mart*Causes rust on leaves and shoots1
P. hieracii var. hypochaeridis (Oudem.) Jørst.*Causes rust on leaves and shoots1
P. punctata Link*Causes rust on leaves and shoots1
P. punctiformis (F.Strauss) Röhl.*Causes rust on leaves and shoots1, 2
P. tumida Grev.*Causes rust on leaves and shoots1
Trachyspora intrusa (Gev.) Arthur*Causes rust on leaves and shoots1
Tranzschelia anemones (Pers.) Nannf.*Causes rust on leaves and shoots1
Trichobasis cichoracearum (DC.) Lév.*Causes rust on leaves and shoots1

Phytoplasmas were observed by Schneider et al. (1997) and multiple inflorescence disease from a phytoplasma was recently recorded in Serbia (Rancic et al. 2005). Cirsium arvense can harbour cucumber mosaic virus (Hanson 2003). Tomato Spotted Wilt Virus was detected in British Columbia (Bitterlich & Macdonald 1993).

X. History

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

The centre of origin of Cirsium arvense is believed to be in the southern Mediterranean and temperate Middle East. The earliest records in the UK of fossil fruits are associated with the presumed open conditions of the opening and closing phases of glacial stages in the Pleistocene. Material has been recorded from the warm inter-glacial Ipswichian and late Weichselian periods. Later records are from the pollen zones VIIb and VIII of the Flandrian period from settlement sites in S. England dating from the Mesolithic period (5000 bc) through the Bronze Age to Roman and Mediaeval times (Godwin 1975). Comparison was drawn by Salisbury (1932, cited by Godwin 1975) of the morainic deposits fringing the Pleistocene glaciers with present artificial conditions of cultivated and disturbed soils as a suitable habitat for ruderal species including C. arvense. Such species could have survived the Flandrian period on cliffs, beaches, river banks and screes until prehistoric man cleared the forests.

Written references to ‘þistil’ (Old English) or ‘thistil’ date from the 8th century and include Caxton, 1481 ‘thystle’ and Turner’s Herbal, 1562 ‘thistel’. Baxter 1650 mentioned the thistle as a ‘bad weed, but growing in good ground’ (Murray et al. 1919). An alternative Scottish spelling was ‘thristle, ‘thristelle’ or ‘thrissel’. The first botanical record from Britain was by Gerarde (1597), under the names: Carduus lanceatus and C. vulgatissimus later as Cnicus lanceolatus Willd. and Cnicus arvensis Bernh., –‘growing by highway sides’ (Clarke 1900). The species generally thought to be the emblem for Scotland is C. vulgare but equally could have been C. arvense. The motto Nemo me impune lacessit derives from the legend of Viking invaders landing on a beach strewn with thistles causing them to shout which warned of their presence (Darwin 1995).

Cirsium arvense was considered a troublesome weed in southern Europe in the early 16th century and throughout Europe by the 18th century (Dewey 1901, cited by Moore 1975). Introduction to North America from Europe was probably early in the 17th century in animal bedding, as a contaminant of farm seed or even as thistle down used to stuff mattresses, and it became well established by the second half of the 18th century (Hansen 1918). One source suggests introduction into New France (Quebec and Ontario) by early French settlers was as a feed for swine, possibly from the roots (Stevens 1847). Seeds entered USA in baled hay from Canada for horses in the Union army in Virginia. This may have given rise to the name Canada thistle. Subsequent spread was rapid and resulted in an early (1797) declaration as a noxious weed (Detmers 1927). Similar introduction to countries in the southern hemisphere (South America, South Africa, Australia, New Zealand) occurred in 19th century travels. It was introduced into New Zealand and spread rapidly particularly in South Island (Saxby 1952). It is now one their most troublesome weeds. It reached serious proportions in Tasmania at the beginning of the 20th century and is still a significant weed. Initial introductions therefore closely follow human travel and once established creeping thistle soon became a noxious weed in temperate regions. In the UK it is now a constituent of many ‘natural’ communities (see III).

Nomenclature

Cirsium is the latinized version of the Greek Kirsion, given to thistle species by Dioscorides and derived from Kirsos = swollen vein, in allusion to the effect when pricked by one of the bristles. Thistles were also said to have been used for the treating of varicose veins. The first recorded description (1616) was attributed to Fabius Calumna, under the name: Ceanothus Theophrastis (Lund & Rostrup 1901).Detmers (1927) further reviewed the history of nomenclature for C. arvense. A description published in 1687 by Tabernaemontanus placed it under Carduus arvensis, a thistle of cultivated fields. Cirsium arvense was first used by Tournefort in 1700 and also in 1772 by Scopoli, the authority now accepted. Equivalent names are: Serratula arvensis L., Carduus arvensis Robs., Carduus arvensis (L.) Sm., Cnicus arvensis Hoffm., Cirsium setosum (Willd.) Bieb., Cirsium incarnum (SG Gmelin) Fischer, Cirsium lanceolatum Hill.

English vernacular names include: creeping thistle, corn thistle, cursed thistle, hard thistle, prickly thistle, way thistle, Californian thistle, Canada thistle, Dashel, san wort. In Welsh, it is ysgallen y maes; in Gaelic, fothannan, aigheannach; in Scots, thrissel, thristle. Other names in Europe are: Croatia, osjak; Czech Republic, pcháč oset; Denmark, agertidsel; Estonia, pōldohakas; Finland, peltoohdake; Flemish, akker distel; France, chardon, cirse des champs; Germany, akerdistel, acker kratzdistel; Greece, yaidouragkatho (non-specific); Iceland, akurþistill; Italy, scardiaccione stoppione; the Netherlands, akker distel; Norway, tissel; Poland, ostrazen polny; Russia, czertoi oloch (the devil’s child); Slovenia, naradin osat; Spain, cardo; Sweden, akertistel; Yugoslavia, palamida. Elsewhere it is called: Chile, cardo; Japan, ezonokitsuneazami; Sanskrit, tejact; South Africa, kanadese dissel; Tunisia, cirse des champs; New Zealand, Cally thistle; USA, Canada thistle.

Uses

The leaves and stems were valued as fodder for cattle in Vermont, USA, in the early 19th century. In some parts of Scotland, owing to its abundance, it was formerly cut regularly for 5–6 weeks in summer to feed cattle (Stevens 1847). The plant was used for fodder and fuel in Afghanistan (von Altschul 1973). At the present day White-tailed deer (Odocoileus virginianus) use senescent C. arvense in Minnesota, USA, as a source of forage which may have higher digestible protein than larger diameter woody twigs (Windels & Jordan 2008). The young developing shoots taken before they emerge from the soil were reported by Rogers (1928) to be tender and tasty when used in the same way as asparagus. Shoots and roots were said to have been consumed in Russia and by Native American Indians. Uses for curdling milk and as a dye have been reported (Darwin 1995). Thistledown was once used to fill mattresses (Hatfield 2009). North American Indian tribes have used extracts of roots as a vermifuge for children and for mouth sickness, and leaf extracts as a mouth wash. Extracts of the whole plant were used for lung troubles and for tuberculosis (Moerman 1998). Ear oedema in mice induced by 12-O-tetradecanoylphorbol-13-acetate could be markedly inhibited by methanol extracts of the flowers of seven Asteraceae species, including C. arvense (Yasukawa et al. 1998). Guarrera (2005) reported the use of C. arvense as an emergency haemostatic in Central Italy, as well as for intestinal disturbances. The effects of the roots on soil aeration and of thistle growth on the suppression of moss were noted by Elliot (1942, quoted by Fairbairn & Thomas 1959). The benefits of C. arvense as a means of alleviating compacted soils were demonstrated in Estonia (Reintam et al. 2008). Soil penetration resistance and bulk density were both significantly lower in thistle areas than under barley. Shoot mass of thistle was less affected than barley by soil compaction and wheat yields on soils affected by thistle were increased by 37% on compacted soil, 28% on loose soil.

Legal

In the UK C. arvense is scheduled as an injurious weed in the Weeds Act 1959 (revised 1972) (HMSO 1959). If ‘growing on any land, the Minister of Agriculture may serve a notice requiring the occupier of the land to take action within a specified time to prevent the weed from spreading’, with penalties of legal proceedings for unreasonable lack of compliance. Alternatively, costs may be recovered from the occupier where control measures were carried out statutorily. On public roads, ‘the occupier’ is the authority maintaining the road. Similar strictures were formerly in force in France and USA (Stevens 1847). During the Second World War, landowners were reminded in summer, by police notices and by local inspection, of their obligation to prevent thistles (and docks, ragwort) from spreading. Since 1959 there are no records of any prosecutions ever having been made under the Weeds Act and no notices relating to thistles have been served in recent years in Scotland (Scottish Executive, pers. comm.). Similar legislation exists in other countries in Europe. In North America, laws have been in place to try and curb the spread of creeping thistle since the 18th century. The first pure seed law was passed in Vermont in 1795, prohibiting thistle seed contamination of grass seeds. Similar legislation was enacted in other states – New York 1931, Ohio 1844, though C. arvense was not recorded there until 1859, and finally Idaho in 1913 (Detmers 1927; Hodgson 1968). In most of the northern states of the United States and provinces of Canada Cirsium arvense was the most frequently listed noxious weed (in 33/38 weed lists) (Skinner, Smith & Rice 2000) and it figures in numerous laws, being listed as a noxious weed in all but four U.S. states (Alaska, Arkansas, Hawaii and New Mexico) by 1957. In Australia it was proclaimed as a noxious weed in Victoria in 1885 (Amor & Harris 1975). The New Zealand Government offered a reward of £250 in 1894 for an effective method of eradication and in 1901 passed a Noxious Weeds Act (Meadly 1957).

XI. Conservation and management

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

Conservation

Though a minor constituent of many natural communities in the UK (see III), C. arvense is generally very competitive against shorter growing species and is considered to have a negative influence in natural plant conservation (Simpson 1993; Peel & Jones 1997). This is certainly true for much of set-aside and grass field margins (Kleijn, Joenje & Kropff 1997) which are allowed to regenerate naturally, when C. arvense can rapidly become locally dominant (Cole et al. 2007), suppressing all but coarser species, such as Rubus fruticosus and Urtica dioica (Bohren, Mermillod & Delabays 2007). Natural colonization or revegetation of wetlands restored from prolonged cropping by interrupting drainage lines in mid-USA often resulted in extensive expansion or dominance of invasive perennials including C. arvense (Mulhouse & Galatowitsch 2003). Laubhan & Shaffer (2006) reported that C. arvense could aggressively invade wetland margins and potentially reduce biodiversity and alter the ecosystems in montane habitats of Colorado and Wyoming, USA. Improved biodiversity in N.E. Montana waterfowl areas resulted from the autumn control of C. arvense by ropewick-applied glyphosate (Krueger-Mangold, Sheley & Roos 2002). Pritekel et al. (2006) found evidence of changes in the composition and functioning of the soil ecosystem in the Rocky Mountain National Park after the invasion and subsequent control of C. arvense. Being a frequent pioneer on waste and neglected land or newly vegetating sites it can be of benefit by providing a plant cover and a guard against soil erosion (Bakker 1960). However, its greatest value in conservation is as a host for a large number of insect visitors (Table 2), arising mainly from the accessibility of copious nectar (Ellis & Ellis-Adam 1992) and strongly scented flowers (see VIII). In addition to pollinating agents such as bees and butterflies, C. arvense is also host to predators of stems, leaves, flowers and seeds (see IX). Clough, Kruess & Tscharntke (2007) confirmed its value for insect biodiversity within arable crops and the enhancing benefit of heterogeneous landscapes on arthropod populations; as a tall herb the creeping thistle gives height and structural diversity. On designated conservation headlands in arable fields (border strips which remain unfertilized and not treated with pesticides, primarily to encourage bird life) some increased insect activity has been associated with the presence of C. arvense (Sotherton 1991). Increased butterfly activity was observed (Dover 1989) and an economically important hoverfly, Episyrphus balteatus Degeer, which deters cereal pests, was attracted by flowering thistles (Cowgill 1989). Assessing the role of weeds in supporting biological diversity in crop fields, Marshall et al. (2003) ranked C. arvense highly for insects which could have an impact on insectivorous bird life, reporting 50 species in 19 insect families on creeping thistle, including five host-specific and four pest species. Cole et al. (2007) recorded increased invertebrate activity in grassland conservation headlands, often associated with an increased abundance of C. arvense.

Crop losses

Evidence of the competitive effect of Cirsium arvense in arable crops comes principally from North America; a review of the extent of yield losses in crops due to its presence was made by Behrens & Elakkad (1981), who considered it to cause greater losses than any other perennial broadleaf weed in the northern part of North America. Yield effects were difficult to quantify because of a non-uniform occurrence in dense patches alternating with thistle-free areas within a crop. Within the dense patches, crop loss could exceed 70%. At a state level, losses in wheat yields were estimated in 1979 to be worth $18 million. In a later review, Donald (1990) quoted data from Hodgson on relative yield losses in winter and spring wheat, barley and oats which increased with increasing thistle shoot density. In this and other studies, relative yield losses increased linearly with thistle densities above 10 m−2 but were more nearly curvilinear at lower densities. O’Sullivan et al. (1982) found significant correlations between barley yield losses and thistle densities, heights, flowering and shoot DMs. O’Sullivan, Weiss & Kossatz (1985) found a linear relationship between rapeseed loss and thistle density. Relative heights and competitive abilities of crop and weed influence the amount of loss and also environmental conditions, e.g. competition for soil moisture in dry seasons or for nutrients in soil of low fertility (Behrens & Elakkad 1981). Models for crop yield loss incorporating relative times of crop and weed emergence were described by Cousens et al. (1987). Examples of the adverse effects on nature conservation areas are noted under Conservation, above.

Added to the direct loss of crop yields, economic losses in handling, processing and quality can result from contamination of seed, grain or crop residues (straw). Thistle flower heads, being of similar size to green peas, can pass through the harvester and contaminate the crop produce (Boldt 1981; G.R. Edwards, pers. comm.). Thistle occurrence has also restricted public access to recreational areas in the United States (Evans 1984). The spines are a source of physical damage to animals causing, for example, orf, a highly contagious virus gaining entry through facial abrasions around the mouths of young lambs (Oswald 1985). Foot problems can be caused and fleece quality affected.

Although C. arvense is widely recognized as a major weed of pastures and forages, herbage yield losses have been measured less frequently than for annual crops. Difficulties include an uneven distribution as in crops, together with the practicalities of sampling in fields under grazing. Oswald (1985) reported that grass DM yields from May to October were not affected by C. arvense populations up to 9 shoots m−2 in spite of increases in plant size through the season. However, utilization by grazing animals was affected, indicated by increases in sward height near the thistle plants. The effects were observed 1 m from a single shoot, 1.4 m from the centre of five shoots and 1.8 m from the centre of clumps of 10–11 shoots. Such rejection of herbage could, for example, lead to reductions in beef liveweight gains. In New Zealand C. arvense reduced the utilization of pastures by sheep resulting in a lower economic output, though cattle were less affected (Hartley & James 1979; Hartley & Thompson 1982). Cirsium arvense and Senecio jacobaea were considered (Bourdôt, Saville & Sunckell 1994) as the most serious weeds affecting the dairy industry in the North Island of New Zealand. In an economic model, Kaye-Blake & Dhakai (2008) projected a potential benefit of between NZ$ 81 million and $153 million over 5 years to the intensive lowland sheep industry if a successful foliage damaging biocontrol agent could be established. Total agricultural losses in lost production and costs of control to New Zealand agriculture attributable to Cirsium arvense were estimated to be several million NZ$.

Mechanical and cultural

See IV.

Chemical control

Early attempts to kill creeping thistle used simple chemicals such as salt, calcium arsenite or sulphuric acid. In the United States salt or apple pomace (which contains malic acid) were applied to make the thistle more palatable to grazing animals (Stevens 1847). Chemical control using hormone herbicides is widely used on cereals and grassland, producing a rapid immediate but limited long-term effect, following a rapid breakdown of the herbicides in the roots (Thind 1975). The pyridine carboxylic acid compound: chlorpyralid (3,6-dichloro-2-pyridine carboxylic acid) with a higher translocation rate than the phenoxy herbicides is more powerful and effective (Marriage 1981; Turnbull & Stephenson 1985). Crop tolerance to clopyralid is much greater and it is widely used mainly in herbicide mixtures, being selective against C. arvense and a number of dicotyledons but not monocotyledons. It is most effective on young thistle becoming less so as the stems grow taller (Donald & Prato 1992). Clopyralid has also been effectively applied by rotary weedwiper (Van Toor 1994).

Non-selective and residual herbicides have been used aiming to eradicate C. arvense on limited areas or on non-crop land. Excellent control of thistle has resulted from the application of the non selective herbicide glyphosate (N-phosphonomethyl glycine) at the bud-bloom stage (Davison 1972; Sprankle, Meggitt & Penner 1975), as there is a rapid translocation from the leaves to underground organs (Sandberg, Meggitt & Penner 1980). Ropewick applications do not usually provide a sufficiently high rate of chemical (Boerboom & Wyse 1988). Combinations of herbicides are sometimes used to reduce costs, broaden application spectrum, achieve synergism and reduce residue problems. Aminopyralid (4-amino-3,6-dichloropyridine-2-carboxylic acid) has proved an effective control when applied at the rosette stage (Egerton, Bailey & Brinkworth 2005). It is applied in mixtures and is approved in the UK for use only for grazed grassland in western Britain under stringent stewardship guidelines (Dow AgroSciences, pers. comm.). Herbicides approved for use on creeping thistle in the UK are listed in Table 6 (Lainsbury 2010). The adoption of GPS equipment has allowed precision mapping of thistle patches in arable crops so that only infested areas are treated with herbicides. In malting barley Gerhards, Dicke & Oebel (2005) achieved a 54% reduction in herbicides for thistle and Kroulik et al. (2008) a 26% reduction in area treated in the Czech Republic using GIS for site-specific application. Hamouz et al. (2008) used airborne multi-spectral imaging to detect C. arvense in winter wheat. In nature conservation areas localized spot or manual treatments with a high labour requirement may be necessary, based on the biology of the weed. Detailed prescriptions for conservation areas in the UK were given by Simpson (1993) and Bond, Davies & Turner (2006); and for the United States by Nuzzo (1997).

Table 6.   Chemicals approved in the UK, 2010, for use as herbicides on creeping thistle (Lainsbury 2010)
Chemical or mixtureCrop
Aminopyralid + fluoroxypyrGrassland
Aminopyralid + triclopyrGrassland
ClopyralidArable crops, vegetables and grassland
Clopyralid + fluroxypyr + triclopyrGrassland
Clopyralid + triclopyrGrassland
2,4-D, 2,4-DBArable crops and grassland
2,4-D + dicamba + dichloroprop-PAmenity grassland, grassland
2,4-D + dicamba + triclopyrGrassland and non-crop land
Dicamba + MCPA + mecoprop-PArable crops and grassland
Dicamba + mecoprop-PArable crops and grassland
GlyphosateNon-crop land, ropewick application in grassland
MCPAArable crops, grassland and non-crop land
MCPBArable crops and grassland
Mecoprop-PArable crops and grassland
Metsulphuron-methyl + thifensulphuron-methylCereals
TriclopyrGrassland, non-crop land
Biological control

With mounting concerns at the widespread use of herbicides investigations into the possibilities of biological control of creeping thistle began in the 1950s. Early work was centred in North America with later studies in New Zealand, both being regions where C. arvense had been introduced and become a serious weed. Reviews of progress in its biological control were published by Schroder (1980), Peschken (1981), Bourdôt & Harvey (1994), Nuzzo (1997) and Bond, Davies & Turner (2006). Table 7 lists the most important organisms considered to date. Nuzzo concluded that current biological control organisms provided little or no control of thistle though possibly weakening or killing individual shoots and that a combination of organisms or of biocontrol agents plus herbicides might prove more effective. The majority of agents studied cause damage to the subaerial parts of thistle: flowers or stems, for example, Urophora cardui (L.) causing stem galls (Lalonde & Shorthouse 1984). Ideally a root-damaging agent is required, though no insect feeders are known to cause serious damage to the roots (Ang et al. 1994a). The root-destroying habits of the pig offer a potential means of eradication on a limited scale on farms, as with bracken, Pteridium aquilinum. This was traditionally used to control thistles in continuous cereal rotations in Sweden (Håkansson 2003) and also in the United States (Stevens 1847).

Table 7.   Invertebrates and fungi that have been studied for biological control of Cirsium arvense
Species, by groupPlant part affectedSource
Invertebrates
ACARI
 Aceria anthocoptes (Nalepa)Leaves, forming galls7
COLEOPTERA
 Altica carduorum (Guérin-Méneville)Stem, root and leaves3
 Apion onopordi Kirby, W.Stem, leaves1
 Cassida rubiginosa Müller, O.F.Leaves1, 2
 C. vibex L.Leaves2
 Ceutorhynchus litura (F.)Leaves, mining3
 Cleonus piger (Scop.)Stem, forming galls8
 Larinus planus (F.)Flowers9
 Lema cyanella (L.)Leaves, flowers2, 12
 Rhinocyllus conicus (Froelich)Flowers10
DIPTERA
 Orellia ruficauda (F.)Flower heads4
 Urophora cardui (L.)Stem and leaves5
 Xyphosia milliaria (Schrank)Flower heads6
HEMIPTERA
 Tingis ampliata (Herrich-Schaffer)Stem, root and leaves2, 11
Fungi
ASCOMYCOTA
Botryosphaeriales
 Phyllosticta cirsii Desm.Leaves17
Diaporthales
 Phomopsis cirsii GroveLeaves13
Helotiales
 Sclerotinia sclerotiorum (Lib.) De BaryStem and leaves15
Mycosphaerellales
 Ascochyta sonchi GroveLeaves20
 Septoria cirsii Neissl.Stem and leaves21
Pleosporales
 Alternaria cirsinoxia Simmons & MortensenStem and leaves16
 Phoma destructiva (Plowr.)Leaves1
 P. exigua Sacc. var. exigua 14
 Stagnospora cirsii DavisStem and leaves19, 22
BASIDIOMYCOTA
Uredinales
 Puccinia punctiformis (Str.) Röhl.Stem and leaves1
Bacteria
 Pseudomonas syringis Van Hall pv tagetis HellmersStem and leaves18

Schroder (1980) concluded that a single species alone will not control C. arvense but that several species which attack the leaves, shoots and possibly roots would be required to deplete the root reserves and kill the plants. The performance of natural enemies of thistle was affected by its chemical and physical characteristics (Walker, Hartley & Jones 2008). Attacks by the seed-feeding tephritid insect Xyphosia militaria (Schrank) reached a threshold at high thistle densities but parasitism of this insect by Hymenoptera was consistently higher when thistles were fertilized. When released in Britain, Altica carduorum Guérin was imperfectly adapted to the climate, suffering high mortality at all stages, low egg-production and damaging only isolated plants (Baker, Blackman & Claridge 1972). In New Zealand an impetus for biological control is the occurrence of thistle in hill country where the intensive methods used on low ground, such as mechanized cutting, herbicides and mob stocking, cannot be applied. Agents under study there include: Cassida rubiginosa, Apion onopordi, Puccinia punctiformis, Phoma destructiva (Plowr) (Cripps 2008). Chalak-Hagighi et al. (2008) developed a dynamic optimisation model which evaluated net monetary benefits of a range of possible control options. Results suggested that the introduction of Apion onopordi with one or more control options was the optimum strategy when thistle populations exceeded 1 shoot m−2.

Plant pathogens (fungi and bacteria) have been investigated as biological control agents, singly, in combination and combined with insects (Bond, Davies & Turner 2006). When successful, aqueous suspensions of spores or bacteria have been applied as mycoherbicide treatments. Severe disease symptoms in C. arvense were caused by Pseudomonas syringae pv. tagetis sprays (Johnson, Wyse & Jones 1996; Tichich & Doll 2006), as has also been observed naturally in the field (IX C). The fungus Sclerotinia sclerotiorum (Lib.) de Bary was successfully used in the control of C. arvense in New Zealand sheep pastures (Bourdôt & Harvey 1994; Bourdôt et al. 1995, 2006; Hurrell, Bourdôt & Saville 2001). Kibbled wheat cultures of mycelium were applied as granules, reducing thistle cover in the field by 55% in the year of treatment. Effects on vigour and height persisted into the following season, confirming work by Brosten & Sands (1986). Septoria cirsii Neissl., a leaf spot on thistle, was proposed as a potential bio-control agent, since it is host-specific, is devastating in the field and produces beta-nitropropionic acid, a phytotoxin affecting seed germination, root elongation and causing leaf damage (Hershenhorn et al. 1993). A combination of Phoma destructiva with a beetle, Cassida rubiginosa, resulted in less efficient control, because the beetle avoided Phoma-infected plants for egg deposition and adult feeding and Phoma infection negatively affected larval development and increased larval and pupal mortalities (Kruess 2002). Thistle plants could recover from inoculations with Alternaria cirsinoxia Simmons & Mortensen in Canada (Green, Bailey & Tewari 2001) and Russia (Gannibal & Berestetskiy 2008), and also from Phoma destructiva in New Zealand (Waipara 2003). Phomopsis cirsii Grove may also have potential as a mycoherbicide since it causes stem canker and dieback in Denmark (Leth, Netland & Andreasen 2008). Isolated shoots of C. arvense are occasionally seen completely killed by a massive rust infection and Puccinia punctiformis (Str.) Röhl. (syn. P. suaveolens (Pers.) Rostr., P. obtegens Tul.ex Fückel) has figured in biological control studies (Bailiss & Wilson 1967; Stojanovic et al. 1993). Resistance to P. obtegens by some thistle clones was observed by Turner et al. (1981) and germination of its teliospores was stimulated by thistle extracts (Turner, Kwiatkowski & Fay 1982). Combination treatments of cutting (Kluth, Kruess & Tscharntke 2003), insect damage (Trumble & Kok 1982; Tipping 1993; Kruess 2002) or with a fungus (Kluth, Kruess & Tscharntke 2005) have produced enhanced control in terms of reduced thistle populations, though without complete destruction. Bacher & Schwab (2000) recorded 50% mortality of thistle plants in ecological compensation areas in Germany with a combination of high levels of competition and herbivory by Cassida rubiginosa. Research is continuing in New Zealand to see to what extent natural enemies can regulate thistle population dynamics in relation to the combined effects of rust and insect attack (Cripps 2008). Recent studies in Naples, Italy, have sought to find novel metabolites with herbicidal properties from some of the fungal pathogens of C. arvense. Compounds isolated include: ascosonchine from Ascochyta sonchi (Evidente et al. (2006); the cytochalasin deoxaphomin from Phoma exigua Sacc. var. exigua cultures (Cimmino et al. 2008); phyllostoxin (an oxazatricycloalkenone) from liquid cultures of Phyllosticta cirsii Desm. (Evidente et al. 2008a,b); nonenolides from cultures of Stagnospora cirsii Davis (Evidente et al. 2008c,d); phyllostictine A from the same fungus (Zonno et al. 2008).

Integrated control

As a further development of synergistic effects and given impetus by a growing trend towards organic methods, the approach of integrated control is now being employed. Biological control can only be a contributory weapon in integrated control strategies (Integrated Pest Management). Trumble & Kok (1982) refer to possible competition between chemical and biological techniques, between introduced and native pests and the need to avoid using herbicides toxic to insects. Integrated cultural and chemical treatments give better control in crops and reduce the likelihood of herbicide resistance in the thistle (Dow AgroSciences 2005). Field trials on integrated control have recently taken place in New Zealand (Mitchell & Abernethy 1993), in Germany involving cutting with mycoherbicides (Kluth, Kruess & Tscharntke 2003), in Canada (Grekul, Cole & Bork 2005) involving grazing with herbicide treatments and in the UK (Pywell 2006, 2010). Mitchell & Abernethy (1993) found that shoot numbers of dense C. arvense in a New Zealand pasture could be reduced by 99% after 2 years by close topping the stems in December followed by rotational grazing by adult sheep. Application of MCPB (4-(4-chloro-o-tolyloxy)butyric acid) in December followed by hard grazing achieved the same results though lax grazing was less effective. An interval was required before grazing after the use of herbicide and the stocking rates must then be intensive to eat out the thistle stalks. A combination of insect defoliation by Cassida rubiginosa with plant competition from Festuca arundinacea and Coronilla varia reduced thistle biomass (Ang et al. 1994a, 1995). In a dry year defoliation gave the greater suppression, in a wet year competition was more important. A synergistic effect between infestation by a weevil Apion onopordi Kirby and plant competition by three grass species in reducing above- and below-ground thistle growth was reported by Freidli & Bacher (2001). Additionally, weevil infestation promoted rust infection of thistle in the following year. Combinations of the weevil Ceutorhynchus litura with needle and thread grass Hesperastipa comata (Trin. & Rupr.) Barkworth, a cool season range species, greatly reduced thistle biomass in glasshouse plantings in the United States (Ferrero-Serrano et al. 2008).

Official recommendations advise a combination of grazing or cutting with chemical control (Davies 2003; Dow AgroSciences, 2005; Pywell 2006). These methods require more refined levels of timing, and have the aim of developing environmentally sustainable but effective weed control strategies.

Control

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

Since the Middle Ages C. arvense has been considered an obnoxious and persistent weed that is difficult to control. In the UK it earned the epithet ‘cursed thistle’ (Sowerby 1801), while in the days of early settlement in the United States and New Zealand its rapid and uncontrollable spread often led to despair and even the abandonment of whole farms (Rogers 1928). In recent decades there have been innumerable references on methods of control. Donald (1990) presented a comprehensive review of both cultural and chemical methods. He concluded that thistle control required a concerted management programme over several years if well-established thistle roots were to be eliminated. The difficulties in control arise from: (i) the extensive underground rooting system which can develop adventitious buds at any point, and (ii) limitations in translocation, which provide a means of escaping control measures imposed on the above-ground shoots. A minimum (5 mm) remnant of root allowed to remain is capable of regenerating new shoots for further vegetative spread (Hamdoun 1972). Prentiss (1889) found that root lengths of 1.6 mm were too small to sprout. Root fragments can also lie dormant if conditions are unfavourable. Forsberg (1962, cited by Friesen 1968) found that 6 mm lateral root sections required 164 days and 12 mm lengths 226 days to decay in moist vermiculite when all developing roots and shoots were removed weekly.

Control measures include two approaches:

  • 1
     At the seedling and post-germination stages. This is the straightforward prevention of spread of viable seeds by cutting the stems before flowering. Under cropping, with cultivations or herbicide treatments, seedlings can be relatively easily controlled. In grassland, seedling establishment is inhibited by the maintenance of dense swards (Edwards, Bourdôt & Crawley 2000).
  • 2
     At the established plant stage, representing the intractable aspect of control. Three main strategies have been employed: mechanical, chemical and biological. More recently, a combination of all three has come into vogue, known as integrated control. The great variations in the degree of control have arisen largely from differences in the extent of influence on the thistle root system.

Acknowledgements

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References

Preparation of this account was originally at the invitation of the late Professor Arthur Willis, a former Editor of the Biological Flora and to whose memory this account is respectfully dedicated. The author is indebted to Professor Anthony J. Davy, current Editor, and the Editorial Board (Dr C.D. Preston, Dr M.C. Proctor, D.T. Streeter, Prof. M.B Usher) for constructive comments. Much help has been received from the Librarians at: SAC Auchincruive, the Universities of Aarhus, Denmark, Brunel, Edinburgh, Glasgow, Massey and Lincoln, New Zealand, Royal Botanic Gardens, Edinburgh, Rothamsted Research Station, IGER, Aberystwyth, the British Library, London, Natural Areas Association, Frank A. Lee Library, New York State AES. Dr Scott Laidlaw, Agri Food and Biosciences Institute, Crossnacreevy and Professor A. J. Davy rendered substantial help in guidance and access to innumerable references and abstracts. Gratitude is also expressed to Mrs Thind for permission to quote from the thesis of the late Dr Thind. Information on vernacular names was provided by D.A. Davies, IGER, the late Dr John Frame, Donald Harrison, Tiina Köster and several European grassland specialists. For a description of pollen grains, I am indebted to palynologists Dr Judith Webb and Dr Patricia Wiltshire; I am also indebted to Gina Morrell and Dr Peter Sell for the leaf diagrams. The help of Dr Ken Davies, SAC Edinburgh, Louise Brinkworth, Dow AgroSciences Ltd, Neil White and Lorraine McEwan, Scottish Executive, Dr Kerry Harrington, AgResearch, Massey University, Palmerston North and Prof. Grant Edwards, Lincoln University, Canterbury, New Zealand, Rebecca Murphy and James Brooks, CAB International, Prof. A. Elgersma, Wageningen, Dr Petr Pysek, Dr Jørgen Eriksen, Aarhus, and Prof. D.J. Read who provided information, Steven Morton, Herbiseed for a sample of seeds, is also much appreciated. Prof. D. Hawksworth and Dr D. Roy greatly assisted with nomenclature. Particular thanks are extended to the staff at the Scottish Agricultural College (SAC) Auchincruive, Kara Craig, Dr Lorna Cole, Karen Crighton, Doreen Paterson, Lorraine Reid, Duncan Robertson and Dr Davy McCracken for their invaluable help and support in the preparation of the text. Staff at the Biological Records Centre (Dr Lena Ward, Dr Chris Preston, Dr D. Roy) are thanked for reference to the insect data base, as is the British Mycological Society for reference to the fungal data base.

References

  1. Top of page
  2. Summary
  3. I. Geographical and altitudinal distribution
  4. II. Habitat
  5. III. Communities
  6. IV. Response to biotic factors
  7. V. Response to environment
  8. VI. Structure and physiology
  9. VII. Phenology
  10. VIII. Floral and seed characters
  11. IX. Herbivory and disease
  12. X. History
  13. XI. Conservation and management
  14. Control
  15. Acknowledgements
  16. References
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