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

by Franz Thonner

1. Fruit drupaceous, one-seeded. Seeds without albumen. Ovary 3-5-celled with 1 pendulous ovule in each cell. Filaments without an appendage. Corolla yellowish-green. Leaves alternate, simple and undivided or of 2 leaflets. Shrubs or trees. [Subfamilies BALANITOIDEAE and NITRARIOIDEAE.] 2
Fruit capsular or separating into several nutlets, several- or many-seeded.
Leaves opposite, at least the lower ones, more rarely all alternate, but then dissected or pinnate with many leaflets. 3
2. Fruit with a very thick endocarp. Ovary 5-celled, surrounded by a cupular disc; ovules attached at the top of the cells. Style rather long; stigma 1. Stamens 10. Petals oblong. Sepals hairy. Leaves with two leaflets. Spiny plants.—Species 3. Central Africa, Sahara,
Egypt. They yield timber, fish-poison, vegetables, medicaments, oily seeds, and edible fruits which are also used as a substitute for soap and for preparing a spirituous drink. “Zachun-oil-tree.” (Agialid Adans.)
(Plate 72.) Balanites Del.
Fruit with a thin endocarp, opening finally by 6 teeth at the top. Ovary
3-celled; ovules attached near the middle of the cells. Style very short; stigmas 3, converging. Stamens usually 15. Petals concave, induplicate-valvate in bud. Sepals fleshy, imbricate in bud. Leaves simple, undivided, fleshy.—Species 2. North Africa and northern
Central Africa. They yield soda and edible fruits which are said to be inebriating. “Nitre bush.” Nitraria L.
3. Leaves pinnately dissected or irregularly many-cleft, alternate. Filaments without an appendage. Ovary 3-4-celled with several or many ovules in each cell. Seeds albuminous. Herbs. [Subfamilies TETRADICLIDOIDEAE and PEGANOIDEAE.] 4
Leaves undivided, unifoliolate, digitate, or pinnate, usually opposite.
Ovary 4-10-, usually 5-celled. [Subfamily ZYGOPHYLLOIDEAE.] 5
4. Leaves pinnately dissected. Flowers small. Calyx 3-4-toothed. Petals
3-4, obovate. Stamens 3-4. Ovary deeply lobed, the lobes incompletely
3-celled, 6-ovuled.—Species 1. North-east Africa. Tetradiclis Stev.
Leaves irregularly many-cleft. Flowers rather large. Sepals 4-5, linear. Petals 4-5, oblong. Stamens 8-15. Ovary slightly lobed, with undivided, many-ovuled cells.—Species 1. North Africa. The seeds are used medicinally, as a condiment, and for dyeing. Peganum L.
5. Leaves unequally pinnate or digitate, rarely unifoliolate; in the latter case disc indistinct and ovules ascending. Filaments without an appendage. Ovary 5-celled with 1-2 ovules in each cell. 6
Leaves equally pinnate or undivided, rarely reduced to the stalk. Disc distinctly developed. Ovules pendulous. 8
6. Leaves alternate, with 4-6 pairs of leaflets. Flowers dioecious. Ovary surrounded by strap-shaped scales. Spiny shrubs.—Species 1. South-west
Africa (Namaland). Neoluederitzia Schinz
Leaves opposite, with 1 or 3 leaflets. Flowers hermaphrodite. Herbs or undershrubs. 7
7. Calyx valvate in bud. Petals none. Disc 5-lobed. Stamens 5. Ovule 1 in each ovary-cell, pendulous. Styles 5, with capitate stigmas. Prostrate undershrubs. Leaflets 3.—Species 2. South and North-east
Africa. Seetzenia R. Br.
Calyx imbricate in bud. Petals 5, rose, violet or yellowish. Disc obscure.
Stamens 10. Ovules 2 in each ovary-cell, suspended from ascending funicles. Style 1; stigma simple.—Species 15. North Africa, northern
Central Africa, and South-west Africa. Some are used medicinally. Fagonia Tourn.
8. Leaves alternate, abruptly pinnate, with 6-8 pairs of leaflets. Flowers large. Sepals saccate at base. Corolla yellow. Disc lobed, with 5 glands projecting into the sacks of the sepals. Stamens 10, unappendaged.
Ovary 5-lobed, with 2 ovules in each cell. Shrubs.—Species
1. East Africa (Somaliland). Kelleronia Schinz
Leaves opposite, at least the lower ones. 9
9. Ovary 10-celled, with 2 ovules in each cell. Calyx valvate in bud. Petals narrow, 3-cleft. Disc cupular, 10-toothed. Stamens 10, with awl-shaped appendages at the base. Fruit winged. Seeds exalbuminous.
Erect, succulent herbs. Leaves undivided, club-shaped.—Species 1.
South Africa. Augea Thunb.
Ovary 4-5-celled. Calyx imbricate in bud. 10
10. Ovary-cells with one ovule in each. Style long; stigma club-shaped. Disc
5-lobed, with five 3-cleft scales opposite the sepals. Stamens 10, appendaged. Fruit capsular. Seeds exalbuminous. Shrubs.—Species
1. South Africa. Sisyndite E. Mey.
Ovary-cells with 2 or more ovules in each. 11
11. Ovary-cells later on transversely chambered, 3-5-ovuled. Style very short, with a large stigma. Disc thin, lobed. Fruit separating into nutlets, bristly or warty, usually with outgrowths. Seeds exalbuminous. Herbs.
Flowers cymose, 5-merous.—Species 12. Some of them have edible
seeds or serve as ornamental or medicinal plants. Tribulus Tourn.
Ovary-cells undivided. Style awl-shaped, with a small stigma. Disc fleshy. Filaments usually appendaged. Fruit capsular. Seeds albuminous.
Flowers solitary or in pairs, whitish or yellowish.—Species
55. Some of them yield soda, edible seeds, medicaments, or poison. Zygophyllum L.

[FAMILY 114.] CNEORACEAE

Shrubs. Leaves alternate, simple, entire, gland-dotted, without stipules. Flowers in cymes, 3-4-merous, hermaphrodite, with an elongated receptacle. Petals free, imbricate in bud. Stamens 3-4, alternating with the petals; filaments without an appendage. Ovary 3-4-lobed, 3-4-celled. Ovules 2 in each cell, one above the other, pendulous, curved. Style simple; stigmas 3. Fruit separating in two 2-celled drupes. Seeds with a curved embryo and fleshy albumen. (Under SIMARUBACEAE.)

Genus 1, species 1. Canary Islands. Used medicinally. (Under Cneorum
L.) Chamaelea Tourn.

[FAMILY 115.] RUTACEAE

Leaves gland-dotted, at least at the margin, rarely (Empleuridium) without dots. Petals free, rarely (Empleurum) wanting. Disc usually present. Anthers versatile, opening inwards or laterally by longitudinal slits. Embryo rather large, the radicle turned upwards.—Genera 33, species 320. (Including AURANTIACEAE and XANTHOXYLEAE.) (Plate 73.)

1. Fruit dehiscent and more or less dry. Carpels, at least when ripe, more or less separate, rarely only one present. [Subfamily RUTOIDEAE.] 2
Fruit indehiscent and more or less fleshy. Carpels usually united, even when ripe, rarely only one present. Shrubs or trees. Leaves compound, but sometimes with a single leaflet. 19
2. Stem herbaceous or woody at the base only. Flowers hermaphrodite.
Corolla yellow. Stamens 8-10. Ovules 2, or more frequently more than
2 in each carpel. Seeds albuminous; embryo curved. [Tribe RUTEAE.] 3
Stem woody. Corolla green, white, red, or violet, rarely (Empleurum) wanting. Fertile stamens 3-5, rarely (Pelea) 8-10. Ovules 2 in each carpel. 4
3. Carpels 2, with 5-6 ovules in each. Flowers 4-merous. Petals entire.
Seeds spiny. Undershrubs. Leaves undivided or 3-parted.—Species
2. German South-west Africa (Hereroland) and Island of Socotra. Thamnosma Torr.
Carpels 4-5. Seeds tubercled.—Species 8. North Africa and northern
Central Africa. Some species yield condiments and medicaments.
“Rue.” (Including Desmophyllum Webb and Haplophyllum Juss.) Ruta L.
4. Seeds albuminous. Corolla greenish or whitish. Leaves usually compound.
[Tribe XANTHOXYLEAE.] 5
Seeds exalbuminous. Corolla white, red, violet, or wanting. Leaves simple, undivided. [Tribe DIOSMEAE.] 7
5. Stamens 8-10. Carpels 4-5. Trees. Leaves alternate, undivided.
Flowers polygamous.—Species 1. Madagascar. (Under Melicope
Forst.) Pelea A. Gray
Stamens 3-5. 6
6. Leaves opposite. Flowers unisexual. Carpels 4-5. Styles united.
Seeds oblong. Unarmed plants.—Species 15. Madagascar and neighbouring islands. Some are used medicinally. Evodia Forst.
Leaves alternate. Carpels 1-5. Styles free or united above.—Species
30. Tropical and South Africa. Some species yield timber, vegetables, condiments, and medicaments. (Including Pterota P. Br., under
Zanthoxylum L.) Fagara L.
7. Carpels 1-2. Fertile stamens 4. Flowers unisexual or polygamous.
Shrubs. [Subtribe EMPLEURINAE.] 8
Carpels 4-5. Fertile stamens 5. Flowers hermaphrodite or polygamous. 9
8. Flowers dioecious. Sepals united at the base. Petals 4. Disc 4-lobed.
Anthers roundish, without terminal glands. Leaves needle-like, three-edged, without glandular dots.—Species 1. South Africa (Cape
Colony). Empleuridium Sond.
Flowers polygamous-monoecious. Sepals united beyond the middle.
Petals wanting. Disc none. Anthers oblong, with a gland at the top.
Ovary beaked. Stigma entire. Leaves linear-lanceolate, flat, glandular-serrate.—Species
1. South Africa (Cape Colony). Used medicinally. Empleurum Soland.
9. Endocarp cartilaginous, adnate at the back and separating from the tubercled exocarp at the margins only. Seeds with thick cotyledons.
Ovules one above the other. Ovary with a long and thin stalk. Staminodes linear, glandulose. Trees.—Species 2. East and South Africa.
[Subtribe CALODENDRINAE.] Calodendron Thunb.
Endocarp separating from the exocarp. Seeds with flat cotyledons.
Ovules usually side by side. Shrubs. [Subtribe DIOSMINAE.] 10
10. Staminodes 5. 11
Staminodes none. 15
11. Style long. Stigma small. 12
Style short or rather short. Stigma capitate or discoid. Inflorescences terminal. 13
12. Petals clawed. Stamens with glabrous filaments and gland-tipped anthers.
Staminodes petaloid, with hairy claws. Disc crenate or lobed. Carpels
2-4. Flowers in terminal umbels or heads, rarely solitary and axillary.—Species
100. South Africa (Cape Colony). Some are used as ornamental or medicinal plants. (Plate 73.) Agathosma Willd.
Petals subsessile, glabrous. Carpels 5. Flowers solitary or in cymes in the axils of the leaves.—Species 20. South Africa (Cape Colony).
Some are used medicinally. Barosma Willd.
13. Petals with a very short, glabrous claw. Anthers ending in a stalked gland. Staminodes exceeding the fertile stamens. Disc lobed. Ovary covered with stalked glands. Flowers rather large.—Species 25.
South Africa (Cape Colony). Several species are used as ornamental or medicinal plants, or as a substitute for tea. Adenandra Willd.
Petals with a long or rather long, usually channelled or bearded claw.
Anthers with a sessile gland or without a gland. 14
14. Petals channelled inside, glabrous. Anthers bearing a sessile gland.
Staminodes adnate below to the petals or enclosed by their channelled claw. Ovary glabrous. Leaves alternate.—Species 6. South Africa
(Cape Colony). Some are used as ornamental or medicinal plants. Coleonema Bartl. & Wendl.
Petals not channelled, usually with a hairy claw. Stamens short. Staminodes very small.—Species 15. South Africa (Cape Colony). Acmadenia Bartl. & Wendl.
15. Style long. Stigma small. Petals with a hairy claw. 16
Style short or rather short. Stigma capitate. Filaments glabrous. 17
16. Disc 5-parted. Filaments and style hairy. Carpels 5. Flowers solitary or in clusters, white.—Species 1. South Africa (Cape Colony). Phyllosma Bolus
Disc entire, urn-shaped. Filaments glabrous. Carpels 3-5.—Species
10. South Africa (Cape Colony). Macrostylis Bartl. & Wendl.
17. Petals sessile, obovate, glabrous.—Species 15. South Africa (Cape
Colony). Some are used medicinally. Diosma L.
Petals clawed, hairy within. 18
18. Petals oblong or lanceolate, slightly exceeding the calyx. Anthers with a terminal gland. Flowers very small.—Species 6. South Africa (Cape
Colony). Euchaetis Bartl. & Wendl.
Petals obovate. (See 14.) Acmadenia Bartl. & Wendl.
19. (1.) Fruit a drupe. Flowers usually unisexual. Stigma sessile or nearly so. [Subfamily TODDALIOIDEAE, tribe TODDALIEAE.] 20
Fruit a berry. Flowers usually hermaphrodite. [Subfamily AURANTIOIDEAE, tribe AURANTIEAE.] 27
20. Fruit 1-celled. Seed 1, exalbuminous. Ovary 1-celled. Petals imbricate in bud. Leaflets 1-3. [Subtribe AMYRIDINAE.] 21
Fruit 2-7-celled or consisting of 2-4 carpels cohering at the base only,
1-3 of them sometimes abortive. Ovary 2-7-celled. 22
21. Flowers hermaphrodite. Fertile stamens 10. Disc cup-shaped. Style long, with a minute stigma. Ovule 1.—Species 1. Equatorial West
Africa (Cameroons). Eriander H. Winkl.
Flowers dioecious. Fertile stamens 4-5. Disc ring-shaped. Style short, with a broad stigma. Ovules 2.—Species 18. Tropical and
South Africa. (Under Toddalia Juss.) Teclea Del.
22. Carpels almost free when ripe, some of them rudimentary. Seeds exalbuminous.
Ovary distinctly 2-4-lobed. Stamens 4. Petals valvate in bud. Leaves digitate. [Subtribe ORICIINAE.] 23
Carpels united up to maturity, forming a 2-7-celled fruit. Ovary not or obscurely lobed. Petals imbricate in bud. [Subtribe TODDALIINAE.] 24
23. Carpels 2, one of them rudimentary at maturity. Seeds with equal cotyledons.
Ovary almost glabrous. Petals oblong. Flowers in racemes.—Species
1. Equatorial West Africa (Gaboon). Diphasia Pierre
Carpels 4, of which 1-3 are rudimentary at maturity. Seeds with unequal cotyledons. Ovary very hairy. Petals oval. Flowers in panicles, unisexual.—Species
4. West Africa. Oricia Pierre
24. Fruit with 2-seeded cells. Seeds albuminous. Flowers 4-merous. Trees.
Leaves digitate, with 5 leaflets.—Species 1. Equatorial West Africa
(Gaboon). Araliopsis Engl.
Fruit with 1-seeded cells. Flowers unisexual. Leaves digitate with
3 leaflets, rarely pinnate with 7-9 leaflets. 25
25. Fertile stamens as many as the petals. Flowers 5-merous. Seeds albuminous; embryo curved. Climbing shrubs. Leaves digitate.—Species 1.
Tropics. Yields condiments and is used in medicine. (Cranzia Schreb.) Toddalia Juss.
Fertile stamens twice as many as the petals. Flowers 2-4-merous.
Embryo straight or almost so. 26
26. Filaments awl-shaped. Flowers 4-merous. Seeds exalbuminous. Shrubs.
Leaves digitate.—Species 1. East Africa. Toddaliopsis Engl.
Filaments flattened. Seeds albuminous.—Species 30. Tropical and
South Africa. Some species yield timber and medicaments. (Under
Toddalia Juss.) Vepris Comm.
27. (19.) Ovary 2-5-celled, with 1-2 ovules in each cell. Stamens twice as many as the petals. [Subtribe LIMONIINAE.] 28
Ovary 5- or more-celled, with 4 or more ovules in each cell. Leaves with
1-3 leaflets. [Subtribe CITRINAE.] 32
28. Ovules solitary in each ovary-cell. 29
Ovules two or more in each ovary-cell. Unarmed plants. 30
29. Flowers solitary or in groups of three in the axils of the leaves, 3-, rarely
4-merous. Calyx toothed. Seeds usually with unequal and lobed cotyledons. Spiny shrubs. Leaflets 3, unequal.—Species 1. Cultivated in the tropics. Yields timber, fragrant flowers, and edible fruits. Triphasia Lour.
Flowers in racemes or panicles, 4-5-merous. Calyx lobed or more deeply divided. Leafstalk winged.—Species 10. Tropics. They yield timber, edible fruits, oily seeds, and medicaments. Limonia L.
30. Style very short, not jointed with the ovary. Leaves unifoliolate.—Species
1. West Africa. Glycosmis Correa
Style long or rather short, jointed with the ovary. Leaves unequally pinnate. 31

RUTACEAE.

FLOW. PL. AFR.