Vigna radiata (L.) R.Wilczek

Global description

Vigna radiata is an erect herbaceous plant or most often with a lianascent tendency, with a stem covered with long brown hairs. The leaves are compound trifoliolate with large leaflets. The terminal leaflet is longer pedunculated than the two lateral leaflets. The latter are disymmetrical. Typically they have a discolored, whitish-green area, semicircular at the base.The stipules are extended below the point of insertion by a single lobe. The flowers are grouped in 4 or more at the top of a long stalk. They are yellow and slightly asymmetrical. The fruit is a linear, dehiscent, cylindrical pod containing about ten brown seeds.

General habit

Vigna radiata is an annual herbaceous creeper or erect plant that can grow to 0.2 to 1.3 m high.

Underground system

Deep taproot.

Stem

The stem is cylindrical, solid, more or less angular, and highly branched. It is up to 1.3 m long and 0.5 cm in diameter. The internodes can be up to 20 cm long. It is covered with long, spreading brown hairs.

Leaf

The leaves are alternate, compound, trifoliolate (rarely 5-foliolate). They are borne on a long stalk 5 to 21 cm long with two stipules at the base, 5 to 18 mm long and 3 to 10 mm wide, lanceolate, peltate with a single lobe below the point of insertion. The stipels are clearly visible (5 to 10 mm long) at the base of the petiolules. The terminal leaflet is borne by a 0.5 to 2 cm long petiolule while the lateral leaflets are subsessile, borne by a 2 to 4 mm long petiolule. The terminal leaflet is symmetrical with two enlarged lobes in the lower third, while the lateral leaflets are disymmetrical, with one half of the leaflet much wider than the other, the greatest width of the leaflet being in the lower quarter. The apex of the leaflets is acuminate, the base is broadly wedge-shaped, rounded or sub-cordate. They are dark green in colour: typically they have a discolored, whitish-green area, semicircular at the base. Both sides are hairless to pubescent. Three clearly visible veins run from the base of the leaf blade.

Inflorescence

The inflorescences are axillary and borne on a long pubescent stalk up to 20 cm long, at the top of which are 4 to 15 flowers.

Flower

The flowers are sub-sessile to short-stalked (2-3 mm). They are papilionaceous, slightly asymmetrical. The calyx forms a tube 3 to 4 mm long at the base, terminating in 5 narrowly triangular lobes 1.5 to 4 mm long. The upper pair is fused into a bifid lobe. The calyx is ciliated. The corolla is yellow to greenish yellow, sometimes with red veins on the inside. The corolla measures 0.6 to 1.2 cm in diameter. The carina has a 1 mm long conical pocket on the left side. There are 10 stamens, 9 of which are fused into a tube and one free. Ovary sessile and hairy, with a style ending in a short beak.

Fruit

The fruit is a linear cylindrical pod set perpendicular to the inflorescence stalk or hanging, 5-9 cm long and 4-6 mm in diameter, slightly compressed between the seeds. The tegument is tawny brown when mature and covered with a short brown pubescence. It is dehiscent at maturity and contains 10-15 seeds.

Seed

The seeds are globose or cubic, 2.5-4 mm long and 2.5-3 mm in diameter, brown with a wrinkled seed coat and a small, flat, white central hilum without an aril.

The cultivated form of Vigna radiata has indehiscent pods containing smooth green seeds.

Origin

Vigna radiata is native to India, South East Asia and Australia.

Worldwide distribution

This species is now widespread throughout tropical Africa and Asia. It is present in New Caledonia, and in the Indian Ocean in the Comoros and Madagascar. It is occasionally found in Central and South America.

https://www.gbif.org/fr/species/2982380