SEARCH

SEARCH BY CITATION

Abstract

  1. Top of page
  2. Abstract
  3. Pseudostachyum Munro (1868, p. 141, t. 4)
  4. Pseudostachyum polymorphum Munro (1868, p. 142, t. 4) ()
  5. Acknowledgements
  6. References

A taxonomic review of the genus Pseudostachyum Munro in Thailand is presented including a description of its morphology, geographic distribution and habitat. An illustrated description of the newly recorded species P. polymorphum Munro, discovered in Thailand, is provided and a doubtful species, P. wakha Brandis ex Camus, is reduced to a synonym of P. polymorphum.

The genus Pseudostachyum was first described by Munro (1868) based on the specimens of P. polymorphum collected by W. Griffith, J. D. Hooker and T. Thomson. It is recognized by its long necked rhizomes, thin culm-walls, triangular culm leaf blades, and compressed globose fruits. Based on morphological data, Pseudostachyum was considered part of the genus Schizostachyum Nees by Holttum (1956, but see Stapleton 1994). However, DNA sequence analyses support their separation and the position Pseudostachyum in the paleotropical woody bamboo subtribe Melocanninae (Yang et al. 2007, Sungkaew et al. 2009, BPG 2012).

Pseudostachyum was a monotypic genus until the name P. wakha Brandis ex Camus was introduced by Camus (1913) based on a sterile Burmese specimen of C. B. Smales (collected in 1902). Unfortunately, fertile specimens of the species have not been collected since it was first described, and thus the features of its inflorescence remain unknown. For a long time P. wakha has been considered an unresolved name due to this lack of flowering material and the loss of its type specimen (Ohrnberger 1999). Thus, Pseudostachyum has subsequently been recognized as consisting of only one species (P. polymorphum) (Stapleton 1994, Xia and Stapleton 2006, BPG 2012). Although P. polymorphum has recently been recorded to occur naturally in Thailand (Sungkaew 2008), it has never been technically reported in any botanical publication. In this revision of Pseudostachyum, we also provide clarifi cation of the status of P. wakha.

Pseudostachyum Munro (1868, p. 141, t. 4)

  1. Top of page
  2. Abstract
  3. Pseudostachyum Munro (1868, p. 141, t. 4)
  4. Pseudostachyum polymorphum Munro (1868, p. 142, t. 4) ()
  5. Acknowledgements
  6. References

Type species: Pseudostachyum polymorphum Munro.

Description

Arborescent, unarmed bamboo. Rhizomes pachymorph with long-necks, forming a clump with diffuse culms. Culms erect or scrambling, tips drooping; internodes terete. Culm leaves deciduous; blades erect; ligules short. Buds at each node solitary. Mid-culm branch complements with several branches at each node, all branches sub-equal in size. Leaves shortly pseudo-petiolate; cross-veins present. Inflorescences an iterauctant (indeterminate), leafy, paniculate. Pseudo-spikelets solitary or several clustered in axils of bracts, each subtended by 1 to several bud-bearing bracts, one empty glume, (1−)2 perfect florets and a vestigial terminal floret; rachilla internodes between the florets elongated, disarticulating below the floret. Lemmas similar to glume; paleas 2-keeled; lodicules 3(−5), persistent. Stamens 6; filaments free. Ovary stalked, glabrous, slender ovoid or linear-oblong, ending in a long rigid style; stigmas 2–3. Caryopses globose, surrounded by persistent glume, lemma, palea and lodicules.

Notes

Having examined the available specimens, we found that each spikelet usually consists of one empty glume, two fertile florets and an incomplete floret. According to Clayton et al. (2006 onwards), the spikelet of Pseudostachyum consists of 1−3 basal sterile florets with one fertile floret and a barren rachilla extension.

Pseudostachyum polymorphum Munro (1868, p. 142, t. 4) (Fig. 1)

  1. Top of page
  2. Abstract
  3. Pseudostachyum Munro (1868, p. 141, t. 4)
  4. Pseudostachyum polymorphum Munro (1868, p. 142, t. 4) ()
  5. Acknowledgements
  6. References
image

Figure 1. Pseudostachyum polymorphum. (A) leafy branchlets, (B) culm leaves on the new shoot (flying shoot), (C) flowering branchlet, (D) spikelet, (E) glume, (F) lemmas, (G) paleas, (H) lodicules, (I) ovary with style, (J) young caryopsis. (A)–(B) S. Sungkaew and A. Teerawatananon 176 (Nat. Hist. Mus. Thailand), (C)–(J) A. Teerawatananon and S. Sungkaew 1102 (Nat. Hist. Mus. Thailand). Drawn by Atchara Teerawatananon.

Download figure to PowerPoint

Based on the same type: Schizostachyum polymorphum (Munro) R. B. Majumdar (1989, p. 282). Type: India. Assam, Nigrigam, 18 Jan 1836, Griffith 6735 (lectotype: K!, fide Stapleton 1994).

Taxonomic synonym: P. wakha Brandis ex. E. G. Camus (1913, p. 162) syn. nov.

Type: Burma. Hmangin daung, Taungya ponzo, 762 m a.s.l. (2500 ft), Mar 1902, Smales s.n (holotype: not found).

Description

Culms 5–20 m tall, 1.2–4.0 cm in diameter; young culms glaucous, with a white waxy ring below each node; internodes 1–25 cm long, with walls thin, 2.5–3.0(−5.0) mm thick (mid-culm portion). Branches developing from the lower quarter or from around the mid-culm upwards. Culm leaves 8–13 cm long ×10–15 cm wide, at top shallowly convex to truncate, on back covered with thick white wax and appressed black hairs; blades narrowly triangular, erect, slightly inflated at base, often slightly wavy, 9–20 cm long, 4.5–6.0 cm wide near the base; auricles small lobes, 0.5–1.0 mm tall, fragile, bearing curved fimbriae; ligules 0.5–1.0 mm tall, with margin irregularly denticulate. Leaves 5–9 per branchlet; blade 15–30 cm long × 2–5 cm wide, glabrous, occasionally sparsely hairy near the base, rounded to acute or attenuate at base, acuminate at apex; pseudo-petiole 0.2–0.5 cm long; leaf sheaths 3–6 cm long, puberulous, with hairy margins; auricles tiny falcate lobes, with margins fringed with bristles up to 1 cm long, sometimes absent; ligules ca 0.5 mm high, irregularly toothed along margin. Pseudo-spikelets 1.5–2.5 cm long; subtending bract chartaceous, ca 4 mm long, sparsely hairy on back. Spikelets 0.5–1.2 cm long; glume 1, chartaceous, 3–4 mm long, mucronate, with ciliate margins, 5–7-nerved; lemmas similar to glume, 4–5 mm long; paleas chartaceous, 4–5 mm long, 2-keeled, keels ciliate, 2-nerved between keels and 3-nerved on each involute margin; lodicules membranaceous, 3(4–5), ciliate. Anthers 3.0–3.5 mm long; filaments free; anther apices mucronate (the connective prolonged beyond the anther apex), glabrous. Fruits compressed globose, 4–5 mm.

Distribution and habitat

The geographic range of P. polymorphum is from tropical to temperate Asia. It is found in highland areas (900–1500 m a.s.l.) of India, Bhutan, China, Burma and Vietnam (Stapleton 1994, Ohrnberger 1999, Xia and Stapleton 2006). We have discovered four additional populations of P. polymorphum in Thailand living at altitudes of 900–1300 m a.s.l. in Phu Rua National Park, Phu Luang Wildlife Santuary, Phu Kradung National Park, Loei pro vince and Phu Hin Rong Kla National Park, Phitsanulok province. This species inhabits only semi-shaded areas, forest edges and gaps of lower montane forest.

Notes

The specimens examined from Thailand differ from the Indian material of Munro (1868) and Gamble (1896) mostly in the number of fertile florets. The Thai specimens have two fertile and one vestigial floret, and they differ in having three lodicules and stigmas. The Indian specimens were described as having one fertile floret and a tendency to have four lodicules and two stigmas. However, the general morphology of the specimens is consistent with P. polymorphum. We feel these slight morphological dif ferences, with the present available material, are insufficient to separate them into species, subspecies or varieties.

Camus (1913) referred the Burmese bamboo named ‘Wakha’ to P. wakha. The protologue was established on Brandis description, which was based on C. B. Smales collection (Smales s.n.) from Hmangin Village, Burma. Among the given characters, Camus (1913) and Brandis (1906) indicated that P. wakha is similar to P. polymorphum but differs in having tufted culms. According to our observations, there are no apparent differences between the species. In addition, we also found that the sterile parts of our P. polymorphum flowering specimens are very similar to the description of Brandis (1906) and Camus (1913).

Additional specimens examined

India, Assam, Griffith 1394 (BM), Griffith 1395 (BM), Griffith 1397 (BM), Griffith 1403 (BM); Nigrigam, 18 Jan 1836, Griffith 6735 (K); Sikkim, Hooker s.n. (K), Aug 1828, Hooker s.n. (K); Latpanchar, 610 m a.s.l. (2000 ft), 3 May 1871, Gammie s.n. (BM). Thailand, Phitsanulok: Phu Hin Rong Kla, 1319 m a.s.l., 9 Jul 2011, A. Teerawatananon and S. Sungkaew 1430 (Nat. Hist. Mus. Thailand); Loei: Phu Luang Wildlife Sanctuary, 1000 m a.s.l., 12 Aug 2004, S. Sungkaew and A. Teerawatananon 176 (Nat. Hist. Mus. Thailand); Phu Rua National Park, 900 m a.s.l., 18 Jun 2010, A. Teerawatananon and S. Sungkaew 1102 (Nat. Hist. Mus. Thailand).

Acknowledgements

  1. Top of page
  2. Abstract
  3. Pseudostachyum Munro (1868, p. 141, t. 4)
  4. Pseudostachyum polymorphum Munro (1868, p. 142, t. 4) ()
  5. Acknowledgements
  6. References

We thank the curators and the staff of the BM and K herbaria for the use of specimens. Thanks to Martin Xanthos for access to material in Kew. We are especially thankful to Bhanumas Chantarasuwan and Dr Anna Trias-Blasi for their help sourcing references and material. This work was supported by the Higher Education Research Promotion, and National Research University Project of Thailand, Office of the Higher Education Commission and the Thailand Research Fund (TRF), Research Grant for New Scholar (MRG5480265).

References

  1. Top of page
  2. Abstract
  3. Pseudostachyum Munro (1868, p. 141, t. 4)
  4. Pseudostachyum polymorphum Munro (1868, p. 142, t. 4) ()
  5. Acknowledgements
  6. References
  • Bamboo Phylogeny Group (BPG) 2012. An updated tribal and subtribal classification for the Bambusoideae (Poaceae). – In: Gielis J. and Potters G. (eds), Proc. 9th World Bamboo Congr., 10–12 Apr 2012, Antwerp, Belgium. pp. 327.
  • Brandis D. 1906. Indian trees. An account of trees, shrubs, woody climbers, bamboos and palms indigenous or commonly cultivated in the British Empire. Archibald Constable and Company Ltd.
  • Camus E. G. 1913. Les Bambusees – monographie, biology, culture, principaux usages. – Lechvalier.
  • Clayton W. D. et al. 2006 onwards. GrassBase – The online world grass flora. – < http://www.kew.org/data/grasses-db.html >, accessed 4 Apr 2012.
  • Gamble J. S. 1896. The Bambuseae of British India. Ann. R. Bot. Gard. Calc. 7: 9597, plate 85.
  • Holttum R. E. 1956. Classification of bamboos. Phytomorphology 6: 7390.
  • Majumdar R. B. 1989. Bambusoideae. – In: Karthikeyan S. et al. (eds), Flora Indicae, enumeratio monocotyledonae. Bot. Surv. Ind. Howrah, Calcutta, pp. 274283.
  • Munro W. 1868. A monograph of the Bambusaceae, including descriptions of all the species. Trans. Linn. Soc. Lond. 26: 141142, tab 4.
  • Ohrnberger D. 1999. The bamboos of the world: annotated nomenclature and literature of the species and the higher and lower taxa. – Elsevier.
  • Stapleton C. M. A. 1994. The bamboos of Nepal and Bhutan, part I: Bambusa, Dendrocalamus, Melocanna, Cephalostachyum, Teinostachyum and Pseudostachyum (Gramineae: Poaceae, Bambusoideae). Edinb. J. Bot. 51: 132.
  • Sungkaew S. 2008. Taxonomy and systematics of Dendrocalamus (Bambuseae; Poaceae). – PhD thesis, Univ. of Dublin.
  • Sungkaew S. et al. 2009. Non-monophyly of the woody bamboos (Bambuseae; Poaceae): a multi-gene region phylogenetic analysis of Bambusoideae s.s. J. Plant Res. 122: 95108.
  • Xia N. H. and Stapleton C. M. A. 2006. Pseudostachyum Munro. – In Wu Z. Y. et al. (eds), Flora of China. Vol. 22. Science Press, Miss. Bot. Gard. Press, pp. 5556.
  • Yang H. Q. et al. 2007. Generic delimitations of Schizostachyum and its allies (Gramineae: Bambusoideae) inferred from GBSSI and trnL-F sequence phylogenies. Taxon 56: 4554.