Keys to the genera of Annonaceae

Authors

  • THOMAS L. P. COUVREUR,

    Corresponding author
    1. Institut de Recherche pour le Développement (IRD), UMR-DIADE, 911, avenue Agropolis, BP 64501, F-34394 Montpellier cedex 5, France
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  • PAUL J. M. MAAS,

    1. Netherlands Centre for Biodiversity, Naturalis (section NHN), Biosystematics Group, Wageningen University, Generaal Foulkesweg 37, NL-6703 BL Wageningen, The Netherlands
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  • SVENJA MEINKE,

    1. Hortus botanicus Leiden, P.O. Box 9516, 2300 RA Leiden, The Netherlands
    2. Netherlands Centre for Biodiversity, Naturalis (section NHN), Leiden University, P.O. Box 9514, 2300 RA, Leiden, The Netherlands
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  • DAVID M. JOHNSON,

    1. Department of Botany-Microbiology, Ohio Wesleyan University, Delaware, OH 43015, USA
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  • PAUL J. A. KEßLER

    1. Hortus botanicus Leiden, P.O. Box 9516, 2300 RA Leiden, The Netherlands
    2. Netherlands Centre for Biodiversity, Naturalis (section NHN), Leiden University, P.O. Box 9514, 2300 RA, Leiden, The Netherlands
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E-mail: thomas.couvreur@ird.fr

Abstract

Identification keys are provided for all genera currently recognized in Annonaceae. Separate keys are presented for the Neotropics (34 genera), Africa-Madagascar (40 genera) and Asia-Australasia (42 genera). These keys are based on a combination of vegetative and fertile characters. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169, 74–83.

INTRODUCTION

Annonaceae are a pantropical family of trees, shrubs and lianas. They play an important ecological role in terms of species diversity, especially in tropical rainforest ecosystems. To date, there are 109 validly described and recognized genera and c. 2440 species (Chatrou et al., 2012; Erkens, Mennega & Westra, 2012). Several family-wide keys to the genera have been published in the past (Engler & Diels, 1901; Hutchinson, 1923; Fries, 1959), with the most recent one by Keßler (1993) published almost 20 years ago. Since then, significant taxonomic changes at the generic level have been made, most of them based on molecular phylogenetic studies at the species and generic levels, with the justification to conserve strictly monophyletic genera (see Table 1 for a complete list). Several different types of changes can be identified, including description of genera new to science (Verdcourt, 1996; Couvreur et al., 2009), elevation to the rank of genus of previously described species from different genera (Chatrou, 1998; Mols et al., 2008), reinstatement of generic names formally sunken into other genera (Surveswaran et al., 2010) and generic names reduced to synonymy with other genera (van Heusden, 1994b; Kenfack et al., 2003; Erkens et al., 2007; Rainer, 2007; Zhou, Su & Saunders, 2009; Zhou et al., 2010). Two new generic names were also described and subsequently synonymized: Craibella R. M. K.Saunders, Y. C. F.Su & Chalermglin (Saunders, Su & Chalermglin, 2004), now synonymized with Pseuduvaria Miq. (Su, Smith & Saunders, 2008), and Cleistopetalum Okada (Okada, 1996), which was synonymized into Polyalthia Blume (Turner, 2010). However, Polyalthia, one of the largest genera in Annonaceae, has been shown to be polyphyletic (Mols et al., 2004; Xue et al., 2011) with the species previously described under Cleistopetalum belonging to a clade (Xue et al., 2011) associated with the conserved name Enicosanthum Becc. (Saunders & Xue, 2011). Finally, some genera still have an uncertain status. Oncodostigma Diels was listed as synonym of Meiogyne Miq. by van Heusden (1994b), but the types species (O. leptoneura Diels) was considered as a ‘dubious name’ (the holotype appeared to be a mixed collection), making the transfer of the name Oncodostigma incomplete. Here, we shall consider Oncodostigma as a ‘confused name’ and will not include it into the key. This issue will require future investigation. Furthermore, the genus Friesodielsia Steenis has been shown to be polyphyletic (Richardson et al., 2004; Chatrou et al., 2012): two clades are recognized, an Asian one sister to Desmos Lour. and Dasymaschalon Dalla Torre & Harms and an African one closely related to the African genus Monanthotaxis Baill. The status of both clades of Friesodielsia is not officially recognized yet, and we shall treat the concerned species under the same name. Finally, the taxonomy of Melodorum Lour., Sphaerocoryne Scheff. ex Ridl. and Mitrella Miq. is ambiguous and these genera are in great need of a revision. Following the traditional circumscription of these taxa, we include the liana groups Sphaerocoryne p.p./Melodorum p.p and the arborescent group of Melodorum p.p./Sphaerocoryne p.p. in the key.

Table 1.  Changes in generic status and new genera within Annonaceae since the publication of the last family-wide key of Annonaceae by Keßler (1993). A-AUS, Asia and Australia. NA, not applicable
 GenusAccepted nameRegionReference
  • *

    This name was officially reduced to synonymy with Polyalthia, but was nevertheless included in the Keßler (1993) key.

  • See Introduction.

  • Although the new name Annickia was given in 1990, it was not adopted in the Keßler (1993) key.

  • §

    This is a nomenclatural proposal and still has to be validated.

New genera    
CleistopetalumEnicosanthumA-AUS(Okada, 1996)
CraibellaPseuduvariaA-AUS(Saunders et al., 2004)
Klarobelia ChatrouNANeotropics(Chatrou, 1998)
Maasia Mols, Kessler & RogstadNAA-AUS(Mols et al., 2008)
Mosannona ChatrouNANeotropics(Chatrou, 1998)
Mwasumbia Couvreur & D. M.JohnsonNAAfrica(Couvreur et al., 2009)
Pseudomalmea ChatrouNANeotropics(Chatrou, 1998)
Sanrafaelia Verdc.NAAfrica(Verdcourt, 1996)
Reinstated generic names    
Drepananthus Maingay ex Hook.f.NAA-AUS(Surveswaran et al., 2010)
Fenerivia Diels*NAMadagascar(Saunders, Su & Xue, 2011)
Genera reduced to synonymy    
Ancana F.Muell.MeiogyneA-AUS(van Heusden, 1994b)
Anomianthus Zoll.UvariaA-AUS(Zhou et al., 2009)
Atopostema BoutiqueMonanthotaxis Baill.Africa(Verdcourt, 1971)
Balonga Le ThomasUvariaAfrica(Zhou et al., 2010)
Chieniodendron Tsiang & P. T.LiMeiogyneA-AUS(van Heusden, 1994b)
CleistopetalumEnicosanthumA-AUS(Turner, 2010)
CraibellaPseuduvariaA-AUS(Su, Chaowasku & Saunders, 2010)
Cyathostemma Griff.UvariaA-AUS(Zhou et al., 2009)
Dasoclema J. SinclairUvariaA-AUS(Zhou et al., 2010)
Deeringothamnus SmallAsimina Adans.USAAbott et al. in prep
Dennettia Baker f.Uvariopsis Engl. & DielsAfrica(Kenfack et al., 2003)
Ellipeia Hook.f. & ThomsonUvariaA-AUS(Zhou et al., 2009)
Ellipeiopsis R. E.Fr.UvariaA-AUS(Zhou et al., 2009)
Enantia Oliv.Annickia Setten & MaasAfrica(van Setten & Maas, 1990)
Fitzalania F. Muell.MeiogyneA-AUS(Chaowasku, Zijlstra & Chatrou, 2011)§
Guamia Merr.MeiogyneA-AUS(van Heusden, 1994b)
Guatteriella R. E.Fr.Guatteria Ruiz. & Pav.Neotropics(Erkens et al., 2007)
Guatteriopsis R. E.Fr.GuatteriaNeotropics(Erkens et al., 2007)
Heteropetalum Benth.GuatteriaNeotropics(Erkens et al., 2007)
Mezzettiopsis Ridl.Orophea BlumeA-AUS(Keßler, 1988)
Oreomitra DielsPseuduvariaA-AUS(Su et al., 2010)
Pachypodanthium Engl. & DielsDuguettiaAfrica(Chatrou, 1998)
Papualthia DielsHaplostichanthus F.Muell.A-AUS(van Heusden, 1994a)
Petalolophus K.Schum.PseuduvariaA-AUS(Su et al., 2005)
Polyaulax BackerMeiogyneA-AUS(van Heusden, 1994b)
Raimondia Staff.AnnonaNeotropics(Rainer, 2001)
Rauwenhoffia Scheff.UvariaA-AUS(Zhou et al., 2009)
Richella A. GrayGoniothalamus Hook.f. & ThomsonA-AUS(Nakkuntod et al., 2009)
Rollinia A.St.-Hil.AnnonaNeotropics(Rainer, 2007)

In total, eight new generic names have been published since 1993, and 31 have been synonymized (Table 1). These changes clearly warrant new keys to the genera of the family. For a complete list of accepted genera, number of species per genus and a family-level classification see Chatrou et al. (2012) and for an annotated list of all generic names ever published in Annonaceae see Erkens et al. (2012).

MATERIAL AND METHODS

We provide identification keys following three major geographical regions: the Neotropics and the USA, Africa (including Madagascar) and Asia/Australasia (including India, Sri Lanka and the Pacific Islands). This approach was taken because most genera are endemic to these major regions. Only seven genera are shared between two regions: Anaxagorea A.St.-Hil. (Neotropics/Asia), Annona L. (Neotropics/Africa), Artabotrys R.Br. (Palaeotropics), Duguetia A.St.-Hil. (Neotropics/Africa), Friesodielsia and Sphaerocoryne (Palaeotropics, but see above), Uvaria (Palaeotropics); and one between them all: Xylopia L. (pantropical). This provides a faster and easier way to identification than a single comprehensive key. For each genus, we also provide an approximate indication of distribution, which can also help with identification. We tried to use vegetative characters as much as possible, but most of these are coupled with fertile ones (flowers and/or fruits). Only macromorphological characters have been retained in the key (e.g. visible with or without a hand lens) in order to make the key useful to a wide range of users. However, in the South-East Asian key an extra pollen character is indicated in parentheses in addition to fertile ones to help identification as these are easily visible using a hand lens (polyads vs. monads).

Key to neotropical genera of annonaceae (Paul J. M. Maas)

  • 1Leaves spirally arranged; flowers tetra-(to hexa-)merous; indument of stellate hairs; Amazon region and French Guiana in the north and Pacific coast of Colombia in the west   Tetrameranthus
  • 1′. Leaves arranged in two rows (distichous); flowers trimerous (rarely dimerous); indument of various types (simple, stellate or scale-like hairs)   2
  • 2Indument of stellate or scale-like hairs (easily visible with a hand lens); fruit syncarpous; carpels strongly coherent, but only partly connate, lower carpels sterile and often forming a basal collar; from Costa Rica in the north to Bolivia and Paraguay in the south, and Africa   Duguetia
  • 2′. Indument of simple hairs or lacking (hairs sometimes stellate in Annona, microscopic stellate to furcate hairs occur in Anaxagorea); fruit either apocarpous or syncarpous, but not as above   3
  • 3Inflorescences axillary (sometimes leaf-opposed in Anaxagorea brevipes) or sometimes arising from trunk (cauliflorous); fruit apocarpous   4
  • 3′. Inflorescences leaf-opposed, supra-axillary, or terminal, rarely arising from trunk; fruit apocarpous or syncarpous   22
  • 4Upper side of leaves with impressed to flat midrib   5
  • 4′. Upper side of leaves with raised midrib   14
  • 5Petals often thick and fleshy (2–10 mm thick) and covered with microscopic, brownish hairs; monocarps club-shaped, explosively dehiscent, two-seeded; throughout Neotropics, except for West Indies, three species in Asia   Anaxagorea
  • 5′. Petals generally much thinner and covered with much larger hairs or glabrous; monocarps never club-shaped, generally globose to ellipsoid, indehiscent, or non-explosively dehiscent, one- to several-seeded   6
  • 6Pedicels with a suprabasal articulation (a few mm above base of pedicel); throughout Neotropics   Guatteria
  • 6′. Pedicels with a basal articulation   7
  • 7Sepals two; petals four; carpels one (or two); Mexico   Tridimeris
  • 7′. Sepals three; petals six; carpels generally numerous   8
  • 8Monocarps dehiscent; seeds distinctly arillate; young twigs mostly lenticellate; leaves generally small and narrow; throughout Neotropics, Africa and Asia   Xylopia
  • 8′. Monocarps indehiscent; aril absent or indistinct; young twigs not lenticellate; leaves mostly much larger and broader   9
  • 9Monocarps several-seeded   10
  • 9′. Monocarps one-seeded   11
  • 10Petals white, maroon, rarely yellow, large, 10–80 × 10–50 mm, distinctly veined; inner petals much shorter than outer ones; monocarps one to 12; south-east USA to southern Canada   Asimina
  • 10′. Petals mostly white, 7–23 × 1–3 mm, with indistinct venation; petals subequal or inner petals longer than outer ones; monocarps one or two; tropical South America, but mainly Amazonian   Diclinanona
  • 11Upper side of leaves with distinctly impressed venation; monocarps long–stipitate (stipes 5–35 mm long); petals 8–12 mm long; tropical South America, but mainly in north-east Brazil   Ephedranthus
  • 11′. Upper side of leaves with flat, not or slightly impressed venation; monocarps short– to long–stipitate; petals 4–70 mm long   12
  • 12Pedicels bearing three to six tiny bracts; stipes of monocarps < 8 mm long; petals 4–8 mm long; flowers bisexual, rarely androdioecious (Oxandra venezuelana), stipes < 10 mm long; throughout Neotropics   Oxandra
  • 12′. Pedicels provided with one or two bracts; stipes of monocarps > 10 mm long, generally much more; petals 7–70 mm long; flowers both staminate and bisexual (staminate and bisexual flowers present)   13
  • 13Pedicels with bract above articulation; petals 8–21 mm long, spreading and leaving floral centre uncovered; raphe of seeds raised, straight; western South America and adjacent Panama   Pseudomalmea
  • 13′. Pedicels without bract above articulation; petals 10–30 mm long, concave, covering floral centre; raphe of seeds impressed, straight, slightly sinuous or spiral; tropical South America up to Cost Rica in the north   Klarobelia
  • 14Petals often fleshy (2–10 mm thick), covered with microscopic, brownish hairs; innermost stamens staminodal; monocarps club-shaped, explosively dehiscent, two-seeded; throughout Neotropics, except for West Indies   Anaxagorea
  • 14′. Petals generally much thinner, covered with much larger hairs or glabrous; all stamens fertile or outermost stamens staminodal (Fusaea); monocarps globose to ellipsoid, indehiscent or non-explosively dehiscent, one- to several-seeded   15
  • 15Leaves with distinct marginal vein, almost touching margin (except in P. spiritus-sancti); petals 4–15 mm long; tropical South America   Pseudoxandra
  • 15′. Leaves without marginal vein (except in Oxandra p.p., but then much further removed from margin); petals 4–35 mm long   16
  • 16Lower side of leaves glaucous; monocarps transversely ellipsoid, one-seeded; petals 25–35 mm long; western part of South America   Ruizodendron
  • 16′. Lower side of leaves not glaucous; monocarps ellipsoid to globose, one- to several-seeded; petals 4–20 mm long   17
  • 17Monocarps one or two, sessile, two- to four-seeded; petals 4.0–8.5 mm long, provided with a small, incurved, tail-like, apical appendage; tropical South America   Onychopetalum
  • 17′. Monocarps generally more numerous (up to 30), mostly distinctly stipitate, often one-seeded; petals 2.5–20.0 mm long, without apical appendage   18
  • 18Leaves asymmetrical; petals 2.5–4.5 mm long; monocarps one-seeded (except in B. pleiosperma), shortly stipitate; tropical South America   Bocageopsis
  • 18′. Leaves symmetrical; petals mostly > 5 mm long; monocarps one- to several-seeded, mostly distinctly stipitate   19
  • 19Upper side of leaves with distinctly grooved midrib; from Costa Rica in the north to Bolivia in the south, eastwards up to the Guianas, and south of the Amazon River   Cremastosperma
  • 19′. Upper side of leaves with non-grooved midrib   20
  • 20Leaves with distinctly raised veins on both sides; petals 10–15 mm long; seeds 25–30 mm long; Amazonian south-west Venezuela and adjacent Brazil   Pseudephedranthus
  • 20′. Leaves with veins on upper side (except for raised midrib) not or indistinctly raised; petals 4–10 mm long; seeds 8–20 mm long   21
  • 21Inflorescences often one-flowered and shortly pedicellate, flower stalk densely beset with 3–6 bracts; apical prolongation of connective tongue-shaped; monocarps one-seeded; throughout Neotropics   Oxandra
  • 21′. Inflorescences often branched, if one-flowered, flower stalk not densely beset with bracts; apical prolongation of connective discoid; monocarps one- to several-seeded; seeds striate to pitted; from Mexico (Oaxaca) in the north to Bolivia, north Paraguay, and southern Brazil in the south   Unonopsis
  • 22Bracts absent   23
  • 22′. Bracts present   29
  • 23Flowers pendent on long (40–60 mm) pedicels; inner petals boat-shaped; throughout Neotropics, except for West Indies   Cymbopetalum
  • 23′. Flowers non-pendent and pedicels much shorter; inner petals not boat-shaped   24
  • 24Leaves asymmetrical; monocarps 20–90 × 30–40 mm, thick-walled (wall 2.5–4.0 mm thick); from Costa Rica in the north through western South America to Bolivia, and south-east Brazil   Porcelia
  • 24′. Leaves symmetrical; monocarps smaller, thin-walled   25
  • 25Petals basally connate   26
  • 25′. Petals free   27
  • 26Petals basally connate into 2–4 mm long tube; monocarps dehiscent, falciform, yellow or orange; aril fleshy, two-lobed; tropical South America   Cardiopetalum
  • 26′. Petals free; monocarps indehiscent, fusiform to linear, green; aril fibrous; western South America    Froesiodendron
  • 27Leaves often triplinerved at base; monocarps three to nine; flower buds globose; stamens c. 40; tropical South America, absent from central Amazon basin   Trigynaea
  • 27′. Leaves not triplinerved at base; monocarps one to three; flower buds globose or conical; stamens < 20; east and south-east Brazil   28
  • 28Flower buds conical; petals linear, recurved to patent; calyx cup-shaped, without distinct lobes; flowers solitary or in many-flowered inflorescences; inflorescences often flagellate and produced from main stem; east and south-east Brazil.   Hornschuchia
  • 28′. Flower buds globose; petals ovate to elliptic, erect; calyx distinctly three-lobed; flowers solitary; east and south-east Brazil   Bocagea
  • 29Upper side of leaves with raised midrib   30
  • 29′. Upper side of leaves with impressed to flat midrib   31
  • 30Fruit apocarpous, monocarps distinctly stipitate; seeds pitted; sepals < 5 mm long; inner base of inner petals with food bodies; from Mexico in the north to Bolivia in the south    Mosannona
  • 30′. Fruit syncarpous, carpels strongly coherent; seeds smooth; sepals > 9 mm long; petals without food bodies; Amazonian Brazil (Upper Rio Negro)   Duckeanthus
  • 31Flowers winged; fruit syncarpous (rarely apocarpous); throughout Neotropics and Africa   Annona
  • 31′. Flowers not winged; fruit apocarpous or syncarpous   32
  • 32Outermost stamens staminodal; fruit syncarpous with almost woody basal collar; tropical South America   Fusaea
  • 32′. All stamens fertile; fruit apocarpous or syncarpous, without basal collar   33
  • 33Fruit syncarpous, each carpel one-seeded; petals often thick and fleshy; throughout Neotropics   Annona
  • 33′. Fruit apocarpous, each monocarp one- to several-seeded; petals thin   34
  • 34Pedicels often with one leafy bract; Mexico and Central America and adjacent northern Colombia   Desmopsis
  • 34′. Pedicels without leafy bracts   35
  • 35Monocarps one-seeded; petals yellow to cream, margins ciliate; from Panama in the north to Peru in the south, also one species in south-east Brazil (Bahia)   Malmea
  • 35′. Monocarps one- to several-seeded; petals red, purple, brown, or rarely cream, margins not ciliate   36
  • 36Petals distinctly veined, length/width ratio 2–5; flowers often with a foetid scent; monocarps 13–100 mm long; seeds with lamellate rumination; Mexico and Central America   Sapranthus
  • 36′. Petals not distinctly veined, length/width ratio 5–20; flowers without a foetid scent; monocarps 10–30 mm long; seeds with spiniform rumination; Mexico, Central America to Pacific coast of Colombia   Stenanona

Key to african and malagasy genera of annonaceae (Thomas L. P. Couvreur & David M. Johnson)

  • 1Indument of stellate or scale-like hairs (easily visible with a hand lens)   2
  • 1′. Indument of simple hairs or lacking   7
  • 2Lower surface of leaf completely covered with silver scale-like hairs; West and Central Africa   Meiocarpidium
  • 2′. Indument of lower leaf surface sparser, not completely covering surface; hairs more stellate than scale-like   3
  • 3Outer petal whorl absent; monocarps stipitate, stipe articulated at apex; West and central Africa, one species in East Africa   Annickia
  • 3′. Outer petal whorl present; monocarps sessile, or if stipitate then stipe not articulated at apex   4
  • 4Trees; fruit syncarpous; West and Central Africa and Neotropics   Duguetia
  • 4′. Scandent shrubs or lianas; fruit of one to many free monocarps   5
  • 5Carpel one; East Africa   Dielsiothamnus
  • 5′. Carpels more than one   6
  • 6Inner petals smaller than outer ones; monocarps moniliform, with seeds in a single row; East Africa   Friesodielsia (F. obovata)
  • 6′. Inner and outer petals subequal; monocarps oblong, with seeds in two rows; throughout tropical Africa, including Madagascar and Asia   Uvaria
  • 7Lianas; inflorescence peduncle formed into a woody hook; throughout tropical Africa including Madagascar and Asia   Artabotrys
  • 7′. Trees, shrubs or lianas; inflorescence peduncle not formed into a woody hook   8
  • 8Upper side of leaves with a raised midrib   9
  • 8′. Upper side of leaves with an impressed to flat midrib   11
  • 9Petals free; flower and fruit apocarpous, inner petals with brush-like structure on inner side; East Africa   Ophrypetalum
  • 9′. Petals fused at base; flowers and fruit syncarpous   10
  • 10Corolla lobes equal in length, margins generally straight; throughout tropical Africa including Madagascar   Isolona
  • 10′. Outer petals longer than inner, margins generally undulated or crisped; throughout tropical Africa   Monodora
  • 11Calyx reduced and vestigial, present as basal flange (sometimes three-lobed); Madagascar   Fenerivia
  • 11′. Calyx not reduced, clearly visible   12
  • 12Sepals free but enclosing petals until anthesis, sometimes reduplicate; monocarps multi-seeded   13
  • 12′. Sepals free but exceeded in length by petals well before anthesis, or sepals connate; monocarps one- or multi-seeded   16
  • 13Petals connate at base, crumpled in bud; throughout tropical Africa   Hexalobus
  • 13′. Petals free to base, not crumpled in bud   14
  • 14Receptacle convex but not columnar; West and Central Africa   Uvariastrum
  • 14′. Receptacle columnar   15
  • 15Small trees; anther connective reduced to a tuft of hairs; West and Central Africa   Mischogyne
  • 15′. Scandent shrubs or lianas; anther connective flattened above anthers; Central and East Africa   Toussaintia
  • 16Sepals completely connate   17
  • 16′. Sepals free, at least at the apex   18
  • 17Trees; calyx forming a flat disk at base of flower; petals six in a single whorl; West Africa   Monocyclanthus
  • 17′. Lianas; calyx entirely enclosing flower in bud, tearing as flower enlarges; petals six in two whorls; Central Africa   Letestudoxa
  • 18Flowers with two sepals; throughout tropical Africa   Uvariopsis
  • 18′. Flowers with three sepals   19
  • 19Lianas with leaf-opposed or terminal inflorescences   20
  • 19′. Trees, or, if lianas, inflorescence axillary   26
  • 20Inner petals shorter than outer ones, vaulted and connivent over stamens and carpels   21
  • 20′. Inner and outer petals subequal, erect or spreading   23
  • 21Anthers septate; monocarps sessile; Cameroon   Boutiquea
  • 21′. Anthers not septate; monocarps stipitate   22
  • 22Leaves glaucous beneath; inner petals with short claw; throughout tropical Africa   Friesodielsia
  • 22′. Leaves sometimes pale beneath, but not glaucous; inner petals lacking claw; east Africa and Asia   Sphaerocoryne
  • 23Monocarps sessile, forming a syncarpous fruit; Central Africa, Gabon   Pseudartabotrys
  • 23′. Monocarps stipitate   24
  • 24Stamens usually < 15; monocarps often many-seeded and moniliform   25
  • 24′. Stamens numerous; monocarps one-(or two-)seeded; Democratic Republic of the Congo   Afroguatteria
  • 25Petals connivent (or rarely imbricate) in bud; stamens obconical; throughout tropical Africa including Madagascar   Monanthotaxis
  • 25′. Petals completely separate in bud; stamens linear; Democratic Republic of the Congo   Gilbertiella
  • 26Flowers with three petals   27
  • 26′. Flowers with six petals   28
  • 27Petals opposite sepals, wood bright yellow, monocarps one-seeded; West and central Africa, one species in East Africa   Annickia
  • 27′. Petals alternate with sepals, wood not bright yellow, monocarps multi-seeded; Central Africa   Uvariopsis (U. tripetala)
  • 28Petals connate at base   29
  • 28′. Petals free   30
  • 29Young branches glabrous; flowers small (< 1 cm), carpels and monocarps solitary; Tanzania, Usambara Mountains   Sanrafaelia
  • 29′. Young branches hairy; flowers large (> 2 cm), carpels and monocarps 5–20; East Africa   Asteranthe
  • 30Monocarps stipitate, stipe articulated at apex   31
  • 30′. Monocarps sessile, or, if stipitate, stipe not articulated at apex   34
  • 31Inner petals shorter than outer ones   32
  • 31′. Inner and outer petals subequal   33
  • 32Anthers septate; monocarps one-seeded, with stipe longer than seed-containing portion; seeds smooth; West and Central Africa   Neostenanthera
  • 32′. Anthers not septate; monocarps two-seeded, with stipe equal in length to or shorter than seed-containing portion; seeds tuberculate; West and Central Africa   Cleistopholis
  • 33Petals linear, acute; introduced in Africa, South-East Asia   Cananga
  • 33′. Petals ovate, obtuse; East Africa   Lettowianthus
  • 34Inner petals much longer than outer ones; West and Central Africa   Piptostigma
  • 34′. Inner petals shorter than or equal in length to outer petals   35
  • 35Fruits syncarpous   36
  • 35′. Fruits apocarpous   37
  • 36Flowers bisexual, borne in leaf-opposed and terminal inflorescences on leafy branches; throughout tropical Africa including Madagascar and Neotropics, introduced in Asia   Annona
  • 36′. Flowers both staminate and bisexual, borne in long pendant leaf-opposed or axillary inflorescences on old branches or stems; West and Central Africa, one doubtful species in East Africa   Anonidium
  • 37Inflorescences leaf-opposed, supra-axillary, or terminal   38
  • 37′. Inflorescences axillary, or plant cauliflorous   39
  • 38Flowers bisexual; petals ovate; anthers septate; monocarps fusiform, sessile; East Africa   Mkilua
  • 38′. Androdioecious; petals linear; anthers non-septate; monocarps globose, stipitate; throughout tropical Africa   Greenwayodendron
  • 39Anthers septate; monocarps dehiscent; throughout tropical Africa, Madagascar, Asia and the Neotropics   Xylopia
  • 39′. Anthers non-septate; monocarps indehiscent   40
  • 40Inner petals smaller than outer ones, deeply concave; monocarps globose with up to 20 seeds in two rows; Central Africa   Exellia
  • 40′. Inner and outer petals subequal, flat or concave; monocarps elongate, or if globose then containing only one or two seeds   41
  • 41Tertiary veins of leaves percurrent; androdioecious; monocarps elongate, seeds pitted; throughout tropical Africa   Polyceratocarpus
  • 41′. Tertiary veins variously curved and anastomosing; flowers bisexual; monocarps elongate or globose; seeds pitted or smooth   42
  • 42Petals < 5 mm long   43
  • 42′. Petals ≥ 10 mm long   44
  • 43Flowers borne singly on leafless branches; monocarps stipitate, one-seeded; East Africa   Cleistochlamys
  • 43′. Flowers multiple in cymose inflorescences; monocarps sessile, two-seeded; Madagascar   Ambavia
  • 44Monocarps long-stipitate, one-seeded, red; East Africa, including Madagascar and Asia   Polyalthia
  • 44′. Monocarps sessile, multi-seeded, green or brown   45
  • 45Carpels 4, ovules and seeds uniseriate; Tanzania, Kimboza Forest Reserve   Mwasumbia
  • 45′. Carpels > 20, ovules and seeds biseriate; throughout tropical Africa   Uvariodendron

Key to asian and australasian genera of annonaceae (Svenja Meinke & Paul J. A. Keßler)

  • 1Lianas   2
  • 1′. Trees or shrubs   10
  • 2Indument of stellate hairs (easily visible with a hand lens); throughout tropical Australasia and (for Uvaria) tropical Africa including Madagascar   Uvaria
  • 2′. Indument of simple hairs or glabrous   3
  • 3Inflorescence peduncle formed into a woody hook; throughout tropical Australasia and tropical Africa including Madagascar   Artabotrys
  • 3′. Inflorescence peduncle not formed into a woody hook   4
  • 4Inflorescences supra-axillary or leaf opposed   5
  • 4′. Inflorescences axillary   7
  • 5Flowers in multiflowered inflorescences; stamen connective tongue-shaped/acute; throughout tropical Asia   Fissistigma
  • 5′. Flowers solitary or in one-flowered inflorescences; stamen connective discoid (uvarioid)   6
  • 6Petals coherent above sexual organs; throughout tropical Asia   Friesodielsia
  • 6′. Petals not coherent above sexual organs; throughout tropical Australasia   Desmos
  • 7Petals coherent above sexual organs   8
  • 7′. Petals not coherent above sexual organs   9
  • 8Petals clawed; stamen connective tongue-shaped/acute; New Guinea   Schefferomitra
  • 8′. Petals not clawed; stamen connective discoid (uvarioid); tropical West Asia   Sphaerocoryne p.p./Melodorum p.p.
  • 9Sepals persisting in fruit; carpels few (10–15); ovules three to five; monocarps globose, < 1 cm in diameter; tropical Australasia except India   Mitrella
  • 9′. Sepals not persisting in fruit; carpels six; ovules six or more; monocarps cylindrical, > 2 cm in diameter; Thailand, Malesia   Pyramidanthe
  • 10Flowers in multiflowered inflorescences   11
  • 10′. Flowers solitary or in one-flowered inflorescences   19
  • 11Petals coherent above sexual organs   12
  • 11′. Petals not coherent above sexual organs   16
  • 12Inner petals longer than outer ones   13
  • 12′. Inner petals shorter than or equal in length to outer ones   14
  • 13Stamen connective not prolonged (miliusoid); stamens few (three to 12); throughout tropical Asia   Orophea
  • 13′. Stamen connective discoid (uvarioid); stamens many (> 30); throughout tropical Australasia   Pseuduvaria
  • 14Petals clawed; ovule one; seed one; tropical Asia except India   Neo-uvaria
  • 14′. Petals not clawed; ovules two to many; seeds two to many   15
  • 15Midrib on upper surface of leaf raised; carpel one; throughout tropical Asia   Cyathocalyx
  • 15′. Midrib on upper surface of leaf flat/impressed; carpels few (two to 20); throughout tropical Asia   Drepananthus
  • 16Flowers unisexual, with carpellate inflorescences at base of main trunk; West Malesia   Stelechocarpus
  • 16′. Flowers bisexual   17
  • 17Stamens many (> 30); carpels many (> 20); throughout tropical Asia   Maasia
  • 17′. Stamens few (< 20); carpel one   18
  • 18Trees up to 30 m tall; sepals and petals valvate; West Malesia   Mezzettia
  • 18′. Treelets up to 5 m tall; sepals and petals imbricate; West Malesia   Dendrokingstonia
  • 19Sepals imbricate   20
  • 19′. Sepals valvate   21
  • 20Inner petals shorter than outer ones; tropical Asia except New Guinea   Sageraea
  • 20′. Inner and outer petals subequal in length; throughout tropical Asia except New Guinea   Enicosanthum
  • 21Petals in one whorl   22
  • 21′. Petals in two whorls   23
  • 22Petals three; anthers not septate, with pollen in monads; monocarps without abscission zone between seed bearing part and stalk (without a stipe); throughout tropical Asia except New Guinea   Dasymaschalon
  • 22′. Petals four to nine; anthers septate, pollen in polyads; monocarps with abscission zone between seed bearing part and stalk (with a stipe); South China to Sumatra and Borneo   Disepalum
  • 23Anthers septate, with pollen in tetrads or polyads   24
  • 23′. Anthers not septate, with pollen in monads   28
  • 24Inner petals coherent above sexual organs   25
  • 24′. Inner petals not coherent above sexual organs   27
  • 25Inner petals spoon-shaped; throughout tropical Asia, Africa and Neotropics   Xylopia
  • 25′. Inner petals clawed   26
  • 26Inflorescences leaf-opposed; throughout tropical Asia   Mitrephora
  • 26′. Inflorescences axillary to slightly supra-axillary or plant cauliflorous; throughout tropical Australasia   Goniothalamus
  • 27Fruits syncarpous; without abscission zone between seed bearing part and stalk (without a stipe); cultivated for its fruits; Neotropics and Africa, introduced throughout tropical Australasia   Annona
  • 27′. Monocarps not connate, with abscission zone between seed bearing part and stalk (with a stipe); cultivated for its flowers; throughout tropical Australasia, introduced in Africa   Cananga
  • 28Ovules three to many   29
  • 28′. Ovule(s) one or two   33
  • 29Petals coherent above sexual organs   30
  • 29′. Petals not coherent above sexual organs   31
  • 30Sepals free; throughout tropical Asia, except New Guinea   Meiogyne
  • 30′. Sepals connate; South Thailand and West Malesia   Platymitra
  • 31Petals saccate; stamen connectives not prolonged (miliusoid); throughout tropical Asia   Alphonsea
  • 31′. Petals not saccate; stamen connectives discoid (uvarioid)   32
  • 32Inflorescences axillary; ovules three to five; tropical Australia   Meiogyne (ex Fitzalania)
  • 32′. Inflorescences supra-axillary; ovules about 10; West Malesia except Philippines   Monocarpia
  • 33Petals clawed   34
  • 33′. Petals not clawed.   35
  • 34Petals coherent above sexual organs; carpels few (< 20); throughout tropical Australasia   Popowia
  • 34′. Petals not coherent above sexual organs; carpels many (> 20); West Malesia   Trivalvaria
  • 35Petals connate   36
  • 35′. Petals free   37
  • 36Petals coherent above sexual organs; ovules two; Philippines, East Malesia, tropical Australia   Haplostichanthus
  • 36′. Petals not coherent above sexual organs; ovule one; Borneo   Woodiellantha
  • 37Inner petals longer than outer ones   38
  • 37′. Inner petals shorter than or equal in length to outer ones   40
  • 38Inflorescences axillary; ovules two; throughout tropical Australasia   Miliusa
  • 38′. Inflorescences supra-axillary or leaf-opposed; ovule one   39
  • 39Petals coherent above sexual organs; tropical West Asia   Marsypopetalum
  • 39′. Petals not coherent above sexual organs; throughout tropical Asia   Phaeanthus
  • 40Stamens few (≤ nine); Sri Lanka   Phoenicanthus
  • 40′. Stamens many (> 30)   41
  • 41Petals spoon-shaped; monocarps dehiscent; throughout tropical Asia, except New Guinea, and throughout Neotropics   Anaxagorea
  • 41′. Petals not spoon-shaped; monocarps indehiscent   42
  • 42Petals coherent above sexual organs; Thailand, Indochina   Melodorum p.p./Sphaerocoryne p.p.
  • 42′. Petals not coherent above sexual organs; throughout tropical Australasia   Polyalthia

ACKNOWLEDGEMENTS

The authors would like to thank Thierry Derion, Lars Chatrou and four anonymous reviewers for their comments and improvements to the keys and text. Richard Saunders is thanked for significantly improving the present article and for sharing his insights about the status of the name Oncodostigma.

Ancillary