The flowering plants of Africa / An analytical key to the genera of African phanerograms

by Franz Thonner

[FAMILY 105.] LEGUMINOSAE

Leaves usually compound and stipulate. Anthers 2-celled. Ovary superior, 1-celled. Ovules inserted at the ventral suture. Style simple, but sometimes with a tooth near the apex. Stigma entire. Fruit 1-, 2-, or transversely several-celled, opening in two valves or along the ventral suture, or separating transversely in two or more joints, or indehiscent.—Genera 261, species 3300 (FABACEAE, including PAPILIONACEAE, CAESALPINIACEAE and MIMOSACEAE.) (Plate 67.)

1. Petals valvate in bud. Flowers regular. Leaves twice pinnate, rarely
(Acacia) reduced to the broadened stalk. [Subfamily MIMOSOIDEAE.] 2
Petals imbricate in bud or wanting. Flowers more or less irregular (sometimes nearly regular.) 28
2. Calyx with imbricate aestivation. Unarmed trees. [Tribe PARKIEAE]. 3
Calyx with valvate aestivation. 4
3. Flowers in long spikes, yellowish. Fertile stamens 5, sterile ones 10-15.—Species
3. West Africa. They yield timber, oil, and edible seeds.
(ovala-seeds) Pentaclethra Benth.
Flowers in globular or club-shaped heads. Fertile stamens 10.—Species
7. Tropics. They yield timber, tanners’ bark, vegetables, medicaments, edible fruits, from which a drink is prepared, and oily seeds, which are also used as a condiment, a substitute for coffee, a fish-poison, and for improving bad water. Parkia R. Br.
4. Stamens as many or twice as many as the petals. 5
Stamens more than twice as many as the petals. Trees or shrubs. 25
5. Anthers without glands. [Tribe MIMOSEAE.] 6
Anthers crowned, at least in the bud, by a sometimes caducous gland.
Stamens 10. 9
6. Fruit dehiscing by two valves which separate from the persistent sutures.
Petals united below. 7
Fruit dehiscing by two valves which do not separate from the sutures, or indehiscent. 8
7. Fruit and seeds slightly 4-angled, the former prickly. Petals red. Stamens
8-10. Herbs or undershrubs. Flowers in heads.—Species 1. West
Africa. Schranckia Willd.
Fruit and seeds flat.—Species 20. Tropics to Egypt, one species naturalized. Some yield timber or medicaments or serve as ornamental plants. Mimosa L.
8. Fruit broadly linear. Seeds placed transversely. Petals free, white.
Stamens 10. Ovary stalked. Unarmed shrubs or trees. Flowers in heads.—Species 1 (L. glauca Benth.). Naturalized in the Tropics. It yields timber, fodder, edible fruits, ornamental seeds, and medicaments. Leucaena Benth.
Fruit narrowly linear. Seeds placed obliquely or longitudinally.—Species
7. One of them naturalized in the Tropics, the others natives of Madagascar.
Seeds used as ornament. (Acuan Medik.) Desmanthus Willd.
9. Seeds albuminous. [Tribe ADENANTHEREAE.] 10
Seeds exalbuminous. [Tribe PIPTADENIEAE.] 19
10. Flowers in heads. 11
Flowers in spikes or racemes. 12
11. Flowers partly (the upper) hermaphrodite, partly (the lower) male or neuter. Ovary stalked. Ovules numerous. Fruit obliquely-oblong, opening by two valves. Herbs or undershrubs. Stipules membranous, cordate.—Species 1. Tropics. Used as a vegetable. Neptunia Lour.
Flowers all hermaphrodite. Ovary sessile. Ovules 1-2. Fruit sickle-shaped, indehiscent. Shrubs. Stipules spinous, recurved.—Species
1. South Africa. Xerocladia Harv.
12. Flowers partly (the upper) hermaphrodite and yellow, partly (the lower) neuter and white or red. Fruit not winged. Shrubs or trees.—Species
12. Tropical and South Africa. Some species yield ebony-like wood and medicaments. (Cailliea Guill. & Perr.) Dichrostachys DC.
Flowers partly hermaphrodite, partly male or female, or all hermaphrodite; no neuter flowers. Trees. 13
13. Fruit winged or distinctly 4-angled, transversely septate, indehiscent. 14
Fruit neither winged nor distinctly 4-angled. 16
14. Fruit 2-winged. Ovary stalked. Flowers sessile.—Species 1. Madagascar and Mauritius. Gagnebina DC.
Fruit 4-winged or 4-angled. Ovary sessile or nearly so. Flowers stalked. 15
15. Fruit 4-winged.—Species 3. Central Africa. They yield timber, a substitute for soap, poison, and medicaments. Tetrapleura Benth.
Fruit 4-angled. Leaves with 4-5 pairs of pinnae.—Species 1. Central
Africa. Amblygonocarpus Harms
16. Fruit distinctly dehiscing in two valves. 17
Fruit indehiscent. 18
17. Seeds few, very flat, winged, with a long funicle.—Species 3. Equatorial
West Africa. Newtonia Baill.
Seeds numerous, thick, red. Leaflets numerous.—Species 1 (A. pavonina
L.). Naturalized in the tropics. It yields timber, gum, dyes, medicaments, and edible oily seeds, which are also used as ornaments. Adenanthera L.
18. Calyx large, tube- or urn-shaped, with ovate, acute teeth. Stamens inserted at the base of the petals. Leaves with one pair of pinnae and several pairs of very large oblong leaflets. Spikes arranged in panicles.—Species 1. Equatorial West Africa (Cameroons). Yields timber and medicaments. Calpocalyx Harms
Calyx small, bell-shaped, with short segments. Stamens free. Leaves with 2-5 pairs of pinnae and small or rather small leaflets.—Species 3.
North and Central Africa. They yield timber and edible fruits. (Including
Anonychium Benth.) Prosopis L.
19. (9.) Flowers in heads. Ovary sessile, with many ovules. Fruit transversely septate. Trees.—Species 5. Tropics. They yield timber and a substitute for soap. (Under Parkia R.Br.) Xylia Benth.
Flowers in spikes or racemes. Shrubs or trees. 20
20. Flowers sessile. 21
Flowers short-stalked. 23
21. Calyx saucer-shaped, cleft to the middle. Petals free. Disc cupular, thick. Fruit large, elliptical, 1-celled. Seeds winged, with a long funicle. Trees. Leaves with 1-2 pairs of pinnae. Spikes panicled.—Species
1. Equatorial West Africa. Yields timber. Fillaeopsis Harms
Calyx bell-shaped, shortly toothed. Disc inconspicuous or wanting. 22
22. Petals obviously united below. Fruit 1-celled, opening in two valves.—Species
13. Tropics to Delagoa Bay. Some species yield ebony-like wood. Piptadenia Benth.
Petals free or nearly so. Fruit with thick, persistent sutures, the valves splitting transversely into one-seeded joints. Endocarp separating from the exocarp and persisting round the seeds. Shrubs.—Species 10.
Tropical and South Africa. Some species (especially E. scandens L. with fruits attaining a yard in length) yield soap-bark, fibre, vegetables, fish-poison, and edible oily seeds which are also used in medicine and as ornaments. (Gigalobium P.Br., Pusaetha L.) Entada Adans.
23. Disc cupular, thin. Ovary stalked. Seeds winged. Trees. Leaves with one pair of pinnae. Flowers with a very short stalk.—Species 1.
Equatorial West Africa. Yields timber. (Including Cyrtoxiphus Harms) Cylicodiscus Harms
Disc inconspicuous or wanting. Ovary sessile or nearly so. Shrubs.
Leaves with 3-12 pairs of pinnae. 24
24. Calyx-teeth more or less unequal. Buds oblique. Fruit woody, transversely septate, opening in two valves. Leaves with 3-6 pairs of pinnae.—Species
1. German East Africa. Pseudoprosopis Harms
Calyx-teeth equal. Fruit leathery, with persistent sutures, the endocarp separating from the exocarp. Leaves with 6-12 pairs of pinnae.—Species
5. South Africa and southern Central Africa. They yield fish-poison and are used in medicine. Elephantorrhiza Benth.
25. (4.) Filaments free or the inner united into a ring. Petals white or yellow.—Species
80. They yield timber, fibre, soap-bark, gum (especially from A. Senegal Willd., Verek), tanning and dyeing materials, perfumes, oil, and medicaments; some are used as ornamental plants. (Including
Vachellia Arn.) [Tribe ACACIEAE.] Acacia Willd.
Filaments united into a tube, at least at the base. Petals white or red.
Flowers in heads. Unarmed plants. [Tribe INGEAE.] 26
26. Fruit strongly curved or coiled, thick, leathery, separating into one-seeded
joints or indehiscent. Petals united beyond the middle. Trees.—Species
3. Tropics; one species naturalized. They yield timber, gum, tanning and dyeing materials, edible fruits, and medicaments. Pithecolobium Mart.
Fruit straight or nearly so. 27
27. Fruit dehiscing elastically. Petals united to the middle. Shrubs.—Species
5. Tropics. They yield timber, gum, and medicaments, and are used also as ornamental plants. Calliandra Benth.
Fruit dehiscing in two straight and thin, not elastic valves, or indehiscent.
Petals united to the middle or beyond.—Species 45. Tropical and
South-east Africa; several species also cultivated in Egypt. Some species (especially A. Lebbek Benth.) yield timber, tanners’ bark, gum, condiments, and medicaments, or serve as ornamental plants. (Including
Zygia Benth.) Albizzia Durazz.
28. (1.) Petals 1-6, the posterior one (the one next the placenta) inside of all in the bud, not forming a papilionaceous corolla, or wanting altogether.
Embryo usually with a straight radicle. [Subfamily CAESALPINIOIDEAE.] 29
Petals 5, the posterior outside in bud, usually constituting a papilionaceous corolla. Sepals united below. Stamens 10, more rarely 5-9. Embryo usually with an inflexed radicle. Leaves simple, unifoliolate, digitate, or once pinnate. [Subfamily PAPILIONATAE.] 104
29. Calyx undivided or shortly lobed in the bud, usually more deeply divided at the time of flowering. 30
Calyx, already in the bud, divided down to the receptacle or nearly so. 39
30. Stamens 1-10. Corolla of 5 petals, nearly regular. Trees or shrubs. 31
Stamens 16 or more. Corolla of 6 petals, or of a single petal, or wanting.
Calyx undivided in bud. Leaves imparipinnate or unifoliolate. Trees.
[Tribe SWARTZIEAE.] 37
31. Leaves undivided, 2-lobed, 2-parted, or of 2 leaflets. [Tribe BAUHINIEAE.] 32
Leaves pinnate, with many leaflets. Stamens 10. 34
32. Ovary and fruit with a very long stalk, the fruit turgid. Ovules few.
Style short. Stamens 10. Petals red. Calyx 5-lobed, imbricate in bud. Climbing shrubs. Leaves undivided, penninerved or faintly trinerved.—Species 3. West Africa. (Bandeiraea Welw.) Griffonia Baill.
Ovary and fruit with a short or rather short stalk, the fruit not turgid. 33
33. Receptacle (calyx-tube) very long. Petals yellowish. Stamens 10, partly sterile. Leaves undivided, ovate or elliptical. Racemes many-flowered.—Species
1. Madagascar. (Under Bauhinia L.) Gigasiphon Drake
Receptacle (calyx-tube) not very long.—Species 40. Tropical and
South Africa, and Egypt. Some species yield timber, fibre, tanning and dyeing materials, edible roots, oily seeds, and medicaments, or
serve as ornamental plants. (Plate 67.) Bauhinia L.
34. Leaves once pinnate, with a terminal leaflet. Calyx campanulate, subequally 5-lobed. Petals subequal, white or red. Ovules numerous.
Fruit opening by two valves. Shrubs. Flowers solitary or in racemes.—Species
8. Madagascar and East Africa. Cadia Forsk.
Leaves twice pinnate. [Tribe DIMORPHANDREAE.] 35
35. Ovary sessile or nearly so. Ovules 2. Style very short. Fruit with a thin, leathery rind, indehiscent. Seeds suborbicular. Flowers in spikes.—Species 2. Central Africa to Transvaal. They yield gum. Burkea Hook.
Ovary stalked. Ovules more than 2. Fruit with a thick, leathery rind.
Flowers in racemes. Trees. 36
36. Calyx-lobes unequal. Petals with a long claw. Stamens with a glandular connective. Style long. Fruit long, wavy, indehiscent. Leaflets small.—Species 1. Madagascar and Seychelles. Brandzeia Baill.
Calyx-lobes subequal. Stamens with a glandless connective. Style short. Fruit oblong, dehiscing by two valves. Seeds oblong. Leaflets large.—Species 5. Tropics. They yield timber, tanning and dyeing materials, medicaments, and poisons especially used in ordeals. “Sassy tree.” (Fillaea Guill. & Perr.). Erythrophloeum Afz.
37. (30.) Corolla of 6 petals, almost regular. Stamens 16-18. Ovary sessile.
Ovules 2. Leaves unifoliolate.—Species 2. West Africa to the
Great Lakes. They yield timber. Baphiopsis Benth.
Corolla reduced to a single petal or wanting. Ovary stalked. Ovules more than 2. Leaves pinnate. 38
38. Receptacle (calyx-tube) very short, almost wanting. Petal 1. Fruit linear.—Species
2. Tropics. Yielding timber. (Tounatea Aubl.). Swartzia Schreb.
Receptacle bell-shaped. Petals none. Fruit ovate.—Species 1 (C. africana Lour.). Central Africa. Yields timber, gum, edible fruits, and medicaments. Cordyla Lour.
39. (29.) Leaves, at least some of them, twice pinnate. [Tribe CAESALPINIEAE.] 40
Leaves all once pinnate, rarely simple. 52
40. Common petiole very short, ending in a spine; rachis of the pinnae very long, flattened, leaf-like; leaflets very small. Stipules spinous.
Trees or shrubs. Calyx imbricate in bud. Petals 5, subequal, yellow.
Stamens 10. Ovules numerous. Fruit linear, tardily dehiscing or indehiscent. Seeds oblong, placed lengthwise, albuminous.—Species 2, one of them a native of South Africa, the other naturalized in the tropics.
They yield timber, bast for paper-making, a substitute for coffee, and medicaments, and serve also as garden- or hedge-plants. Parkinsonia L.
Common petiole distinctly developed; rachis of the pinnae not leaf-like. 41
41. Stem herbaceous or woody at the base only. Petals 5, subequal, yellow.
Stamens 10. Ovules numerous. Fruit dehiscing by two valves, membranous or thin-leathery. Seeds transverse, ovoid, exalbuminous.—Species
3. South Africa and southern Central Africa. (Melanosticta
DC.) Hoffmannseggia Cav.
Stem woody throughout, shrub- or tree-like. 42
42. Flowers sessile, in elongate panicled spikes. Calyx 5-cleft, with semiorbicular lobes. Petals 5, equal, oblong, much exceeding the calyx. Stamens
10, unequal. Anthers basifixed. Ovules 2-3. Trees.—Species 1.
West Africa (Cameroons). Stachyothyrsus Harms
Flowers more or less stalked, in racemes or panicles. 43
43. Flowers polygamous. Calyx slightly imbricate in bud. Petals 3-5, subequal, white or greenish. Stamens 6-10. Seeds transverse, albuminous.
Trees. Leaves without stipules.—Species 2, one a native of
Central Africa, the other naturalized in North Africa. Used as hedge-plants and yielding timber. Gleditschia L.
Flowers hermaphrodite. Stamens 10. 44
44. Petal 1, greenish-yellow. Calyx valvate in bud. Ovules very numerous.
Styles long. Trees.—Species 1. Madagascar. Aprevalia Baill.
Petals 5. 45
45. Sepals united high up, excepting one, valvate in bud. Petals unequal, red. Ovules numerous. Fruit straight, turgid, dehiscing by two valves. Seeds transverse. Trees. Bracts coloured.—Species 1.
Madagascar. Used as an ornamental plant. Colvillea Boj.
Sepals free above the receptacle. 46
46. Sepals valvate in bud. Petals yellow or red. Ovules numerous. Style thread-shaped. Fruit dehiscing by two valves. Seeds transverse, oblong, albuminous. Trees. Stipules indistinct. Flowers large.—Species
3. Tropics; also cultivated in various regions. Ornamental plants. “Flame-tree.” Poinciana L.
Sepals imbricate in bud. Seeds exalbuminous. 47
47. Ovule 1, very rarely ovules 2. Seed 1, placed lengthwise. Fruit winged at the top, indehiscent. Petals subequal, white or yellow. Spinous climbing shrubs. Flowers small.—Species 1. Abyssinia. (Cantuffa
Gmel.). Pterolobium R.Br.
Ovules 2 or more. Seeds placed transversely. 48
48. Fruit woody, not winged, 2-seeded, opening by two valves. Ovary short-stalked,
2-ovuled. Stigma peltate. Stamens hairy at the base. Petals unequal. Receptacle oblique.—Species 2. German East Africa.
(Under Peltophorum Vog.). Bussea Harms
Fruit membranous or leathery. 49
49. Fruit winged at both sutures, indehiscent. Stigma broad-peltate. Filaments hairy at the base. Petals subequal, yellow. Trees—Species 1.
Central Africa and northern South Africa. Peltophorum Vog.
Fruit winged at one suture only or not winged. Stigma small, sometimes
concave. 50
50. Fruit winged, indehiscent. Receptacle (calyx-tube) very oblique. Petals subequal, yellow. Stamens bent downwards.—Species 5. West
Africa and Madagascar. Mezoneurum Desf.
Fruit not winged. Receptacle not very oblique. 51
51. Fruit membranous, lanceolate, dehiscing in the middle of the valves.
Seeds oblong. Sepals subequal. Petals oblong, subequal, yellow.
Stamens erect, hairy at the base. Ovary short-stalked. Ovules 2-3.
Trees.—Species 1 (H. campecheanum L.). Cultivated in the tropics.
Yields timber (log-wood), dyes, gum, and medicaments, and serves also as a garden- and hedge-plant. Haematoxylon L.
Fruit leathery, dehiscing at the sutures or indehiscent. Seeds ovoid or globose. Petals yellow or red. Stamens bent downwards. Ovules few.—Species 10, of which 7 are natives of tropical and South Africa,
3 naturalized there as well as in Egypt and Madeira. They yield timber, tanning and dyeing materials, oily seeds, and medicaments, and are also used as garden- and hedge-plants. (Including Guilandina L.). Caesalpinia L.
52. (39.) Anthers attached by the base or nearly so, rarely by the back, and then opening by apical pores. Seeds usually albuminous. [Tribe
CASSIEAE.] 53
Anthers distinctly attached by the back, opening by longitudinal slits.
Seeds usually exalbuminous. Trees or shrubs. 58
53. Petals 1-2 or 0. Ovules 2-3. Fruit indehiscent, 1-2-seeded. Trees.
Leaves unequally pinnate. 54
Petals 3-5. 55
54. Stamens 2-3.—Species 10. Tropics. They yield timber and edible fruits from which an intoxicating drink is prepared. Dialium L.
Stamens 8-10. Petals none.—Species 1. East Africa. Yields timber. Andradia Sim
55. Petals 3, narrow, yellow. Fertile stamens 2; anthers opening by a terminal pore. Staminodes 3, petaloid. Ovules 4-5. Trees. Leaves unequally pinnate.—Species 1. Equatorial West Africa. Yields timber. Distemonanthus Benth.
Petals 5. Stamens 4-10. 56
56. Sepals 4. Petals unequal, red. Stamens 4-5, some of them with cohering anthers. Ovules 2. Fruit 4-winged. Leaves unequally pinnate.—Species
1. Equatorial West Africa. (Oligostemon Benth.) Duparquetia Baill.
Sepals 5. Leaves equally pinnate or simple. 57
57. Leaves simple, undivided. Stamens 10. Filaments thickened above.
Anthers opening below the top. Ovules few. Fruit fleshy, with transverse partitions. Trees.—Species 2. Madagascar. Baudouinia Baill.
Leaves pinnate.—Species 40. They yield timber, gum, tanning and dyeing materials, fish-poison, medicaments (especially senna-leaves),

fodder, vegetables, edible fruits, and a substitute for coffee; several species are used as ornamental plants. Cassia L.

58. (52.) Ovules 2, rarely 3 or 1, occasionally in some flowers 4. Ovary or its stalk usually free at the base of the receptacle, more rarely adnate to it. [Tribe CYNOMETREAE.]. 59

Ovules 4 or more, occasionally in some flowers only 3. Ovary or its stalk usually adnate to the receptacle by the back. Leaves pinnate. [Tribe AMHERSTIEAE.] 80

59. Petals none. 60

Petals 1-5. 64

60. Sepals 6, very small and unequal. Stamens 6. Ovary sessile. Shrubs. Leaves pinnate. Bracteoles large.—Species 1. Southern West Africa (Congo). Dewindtia De Wild.

Sepals 4-5. Stamens 8-10 or 4. Trees. Leaves abruptly pinnate. Bracteoles small or wanting. 61