Mucuna occidentalis (Hepper) T.M.Moura & G.P.Lewis

Moura, T.M. & Lewis, G.P. 2014. Taxonomic studies in the Mucuna poggei complex (Leguminosae: Papilionoideae). Kew Bulletin 69: 9544. https://doi.org/10.1007/s12225-014-9544-7

Morphology General Habit

Lianas with short hairs on the stems

Morphology Leaves

Leaves alternate, 3-foliolate; stipules caducous; petiole 7.5 – 20 cm long, rachis 2 – 3 cm long; stipels linear, 1 – 4 mm long, persistent; petiolules 7 – 10 mm long; the apical leaflet obovate to elliptic, 7 – 15.5 × 7.5 – 11 cm, obtuse to rounded at base, acute at apex, the lateral leaflets asymmetrical, 10.5 – 16.5 × 8 – 15 cm, obtuse, rounded or slightly subcordate at base (some sinuose along the proximal margin of the base), acute to acuminate at apex, the hairs short and sparse on the abaxial surface of the leaflets

Morphology Reproductive morphology Inflorescences

Inflorescence a pseudoraceme; peduncle 3 – 12 cm long; rachis 14 – 30 cm long; bracts caducous; pedicels c- 1 cm long, 3 flowers per fleshy node

Morphology Reproductive morphology Flowers

Flowers 6 – 8 cm long

Morphology Reproductive morphology Flowers Calyx

Calyx brownish (R. A. A. Oldeman 284, K) or greenish brown, reddish brown hairy, with irritating hairs (W. J. J. O. de Wilde 789, K), sericeous, campanulate, with appressed hairs 1.9 – 2.5 cm long on outer and inner surfaces; lobes 4, the adaxial one formed by two connate sepals, the abaxial one 7 – 12 mm long, the other two lobes 4 – 5 mm long.

Morphology Reproductive morphology Flowers Corolla

Corolla white (R. A. A. Oldeman, 284 K), whitish, tinged greenish (W. J. J. O. de Wilde 789, K) or cream-coloured, slightly tinged green in parts, often with irregular blue-black margins (F. C. Deighton 5600, K); standard 4.2 – 4.5 × 3 – 3.7 cm, broadly elliptic to obovate, rounded at apex and sagittate at base, the claw c. 3 – 4 mm long, glabrous; wing petals 6 – 7.5 × 1.5 – 3 cm, oblong to obovate, basally attenuate, apically rounded to obtuse, pubescent at base, the claw c. 4 – 6 mm long; keel petals 6 – 7.5 × 1.5 – 2 cm, oblong, attenuate at base, acute to obtuse at apex, pubescent at base, the claw 6 – 8 mm long.

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 10, diadelphous, with nine stamens fused, one free; filaments 4.5 – 7 cm long, glabrous; anthers dimorphic, five of them deltoid, 3 mm long, basifixed, the other five globose, 2 mm long, dorsifixed

Morphology Reproductive morphology Flowers Gynoecium

Gynoecium 6 – 7.5 cm long; ovary sessile, oblong, c- 3 × 1 mm, densely sericeous; style 5 – 6.5 cm long, densely sericeous, glabrescent at apex, the stigma peltate

Morphology Reproductive morphology Fruits

Fruit indehiscent, oblong, the surface covered by reddish irritating hairs

Morphology Reproductive morphology Seeds

Seeds circular, and laterally compressed, 1.5 × 1.7 cm, dark brown, hilum brown, 12 mm long

Distribution

Mucuna occidentalis occurs mainly in the West of the African Continent in: Burkina Faso, Ghana, Cameroons, Central African Republic, Togo, Democratic Republic of Congo, Ivory Coast, Liberia, Nigeria and Sierra Leone (Map 1).

Ecology

This species is reported from gallery forest, along river banks, in seasonally inundated grassland and savanna.

Note

Mucuna occidentalis differs from M. poggei mainly in the short sparse hairs on the abaxial surface of the leaflets in M. occidentalis vs the long dense hairs in M. poggei; in the 1 – 4 mm long stipels in M. occidentalis vs 5 – 6 mm long in M. poggei; the 7 – 12 mm long abaxial calyx lobe in M. occidentalis vs c. 5 mm long in M. poggei; and the deltoid basifixed anthers in M. occidentalis vs oblong in M. poggei. Although the two taxa are morphologically similar in fruit characters, we consider M. occidentalis a distinct species based on the differences listed above. In addition, the two taxa only overlap in geographical distribution in the Democratic Republic of Congo — M. occidentalis occurs in the west of the African Continent (Sierra Leone to the north of the Democratic Republic of Congo), whilst M. poggei occurs mainly in the east and southeast.

Two type specimens together with a carpological box (Deighton 5600) are housed in herbarium K. The two type sheets have Kew barcode numbers K 263326 and K 263327. One of these (K 263327) consists of branches and inflorescence rachises without any leaf or flower, while the other (K 263326) comprises two small packets, one containing flowers and the other leaflets, petioles and petiolules but no stems or inflorescence rachises. It is clear that the packets on sheet K 263326 contain plant fragments fallen from sheet K 263327. The fruits in the carpological collection are also part of the original collection that were too bulky to be mounted on the herbarium sheet. We therefore consider that lectotypification is not necessary because there is no ambiguity about the type collection. We consider Deighton 5600 (K) to be the holotype comprising three elements: two herbarium specimens and one carpological box.