Key to the genera of African Annonaceae

Thomas L.P. Couvreur & David M. Johnson (PDF)

1.    Indument of stellate or scale-like hairs (easily visible with a hand-lens). 2
1'.    Indument of simple hairs or lacking. 7

2.    Lower 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

3.    Outer petal whorl absent (3 petals alternate to sepals); monocarps stipitate, stipe articulated at apex [West and central Africa, 1 species in East Africa]. Annickia
3'.    Outer petal whorl present; monocarps sessile, or if stipitate then stipe not articulated at apex. 4

4.    Trees; fruit syncarpous [West and Central Africa and Neotropics]. Duguetia
4'.    Scandent shrubs or lianas; fruit of 1–many free monocarps. 5

5.    Carpel 1 [East Africa]. Dielsiothamnus
5'.    Carpels > 1. 6

6.    Inner 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 2 rows [throughout tropical Africa including Madagascar and     Asia]. Uvaria

7.    Lianas; 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

8.    Upper side of leaves with a raised midrib. 9
8'.    Upper side of leaves with an impressed to flat midrib. 11

9.    Petals 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

10.    Corolla 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

11.    Calyx reduced and vestigial, present as basal flange (sometimes 3-lobed) [Madagascar]. Fenerivia  
11’.    Calyx not reduced, clearly visiblE. 12

12.    Sepals 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-seeded or multi-seeded.16

13.    Petals connate at base, crumpled in bud [throughout tropical Africa]. Hexalobus
13'.    Petals free to base, not crumpled in bud. 14

14.    Receptacle convex but not columnar [West and Central Africa]. Uvariastrum
14'.    Receptacle columnar. 15

15.    Small 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

16.    Sepals completely connate. 17
16'.    Sepals free, at least at the apex. 18

17.    Trees; calyx forming a flat disk at base of flower; petals 6 in a single whorl [West Africa]. Monocyclanthus
17'.    Lianas; calyx entirely enclosing flower in bud, tearing as flower enlarges; petals 6 in two whorls [Central Africa]. Letestudoxa

18.    Flowers with 2 sepals [throughout tropical Africa]. Uvariopsis
18'.    Flowers with 3 sepals. 19

19.    Lianas with leaf-opposed or terminal inflorescences. 20
19'.    Trees, or, if lianas, inflorescence axillary. 26

20.    Inner petals shorter than outer ones, vaulted and connivent over stamens and carpels. 21
20'.    Inner and outer petals subequal, erect or spreading. 23

21.    Anthers septate; monocarps sessile [Cameroon]. Boutiquea
21'.    Anthers not septate; monocarps stipitate. 22

22.    Leaves 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

23.    Monocarps sessile, forming a syncarpous fruit [Central Africa, Gabon]. Pseudartabotrys
23'.    Monocarps stipitate. 24

24.    Stamens usually < 15; monocarps often many-seeded and moniliform. 25
24'.    Stamens numerous; monocarps 1(–2)-seeded [DRC]. Afroguatteria

25.    Petals connivent (or rarely imbricate) in bud; stamens obconical [throughout tropical Africa including Madagascar]. Monanthotaxis
25'.    Petals completely separate in bud; stamens linear [DRC]. Gilbertiella

26.    Flowers with 3 petals. 27
26'.    Flowers with 6 petals. 28

27.    Petals opposite sepals, wood bright yellow, monocarps single-seeded [West and central Africa, 1 species in East Africa]. Annickia
27'.    Petals alternate with sepals, wood not bright yellow, monocarps multi-seeded [Central Africa]. Uvariopsis (U. tripetala)

28.    Petals connate at base. 29
28'.    Petals free. 30

29.    Young 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

30.    Monocarps stipitate, stipe articulated at apex. 31
30'.    Monocarps sessile, or, if stipitate, stipe not articulated at apex. 34

31.    Inner petals shorter than outer ones. 32
31'.    Inner and outer petals subequal. 33

32.    Anthers septate; monocarps 1-seeded, with stipe longer than seed-containing portion; seeds smooth [West and Central Africa]. Neostenanthera
32'.    Anthers not septate; monocarps 2-seeded, with stipe equal in length to or shorter than seed-containing portion; seeds tuberculate [West and Central Africa]. Cleistopholis

33.    Petals linear, acute [Introduced in Africa, South East Asia]. Cananga
33'.    Petals ovate, obtuse [East Africa]. Lettowianthus

34.    Inner petals much longer than outer ones [West and Central. Africa] Piptostigma
34'.    Inner petals shorter than or equal in length to outer petals. 35

35.    Fruits syncarpous. 36
35'.    Fruits apocarpous. 37

36.    Flowers 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

37.    Inflorescences leaf-opposed, supra-axillary, or terminal. 38
37'.    Inflorescences axillary, or plant cauliflorous. 39

38.    Flowers 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

39.    Anthers septate; monocarps dehiscent [throughout tropical Africa, Madagascar, Asia and the Neotropics]. Xylopia
39'.    Anthers non-septate; monocarps indehiscent. 40

40.    Inner petals smaller than outer ones, deeply concave; monocarps globose with up to 20 seeds in 2 rows [Central Africa]. Exellia
40'.    Inner and outer petals subequal, flat or concave; monocarps elongate, or if globose then containing only 1–2 seeds. 41

41.    Tertiary 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

42.    Petals < 5 mm long. 43
42'.    Petals 10 mm long or longer. 44

43.    Flowers borne singly on leafless branches; monocarps stipitate, 1-seeded [East Africa]. Cleistochlamys
43'.    Flowers multiple in cymose inflorescences; monocarps sessile, 2-seeded [Madagascar]. Ambavia

44.    Monocarps long-stipitate, 1-seeded, red [East Africa including Madagascar and Asia]. Polyalthia
44'.    Monocarps sessile, multi-seeded, green or brown. 45

45.    Carpels 4, ovules and seeds uniseriate [Tanzania, Kimboza Forest Reserve]. Mwasumbia
45'.    Carpels > 20, ovules and seeds biseriate [Throughout tropical Africa]. Uvariodendron

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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith