Desmodium tortuosum (Sw.) DC.

Global description

Desmodium tortuosum is an herb or an erected sub shrub, 0.4 to 2 meters high. The branches are covered with hooked hairs and long, sparse hairs. The leaves are alternate, composite, trifoliate. At the base of the petiole are persistent stipules with largely asymmetrical base. The leaflets are narrowly oval, almost diamond-shaped, hairy on both surfaces and more densely on the margin. The margin is entire. The inflorescences are terminal or axillary racemes sometimes grouped in large panicles leaves. The flowers are inserted in small groups of 2 or more, carried by a pedicel of 8 to 15 mm. They are usually pink or purple sometimes white or yellow. The fruit is a pod, 1 to 3 cm long, ending in a very short tip. It consists of 3 to 7 circularto elliptical articles inter-connected by a narrow median isthmus.
 
Cotyledons

Cotyledons are stalked, with broadly ovate lamina. The base and top are rounded. They are poorly persistent
 
First leaves

The first leaves are alternate, stalked with largely asymmetrical oval stipules at the base. The first two leaves may seem to be opposite to a first very short node. The very first leaves are simple, with a blade ovate to oblong, then become composed with 3 leaflets. The leaflets are narrowly ovate to almost diamond-shaped, terminal leaflet are longer stalked than the laterals. They are green on both sides, pubescent with densely pubescent, entire margin.
 
General habit

Herbaceous plant, lignified, with erect habit, reaching 0.4 to 2 m high
 
Underground system

The plant has a main taproot.
 
Stem

The stem is full, cylindrical. It is densely pubescent, covered with hooked hairs and longer straight hairs, scattered, sometimes tuberculate at the base, particularly at the inflorescence. It is often purple.
 
Leaves

The leaves are alternate, compound, trifoliate. They are carried by a pubescent petiole of 2 to 5 cm long. It is framed at the base by two persistent stipules, oblique, ovate with widely asymmetrical base and attenuated apex, 6 to 13 mm long. The leaflets are narrowly ovate, almost rhomboid, 2 to 9 cm long and 1 to 4 cm wide. The terminal leaflet is longer than the lateral leaflets. The leaflets are sub sessile having reduced stipels, the terminal leaflets is at the end of a rachis 4 to 8 times longer than petiolules. The lamina of the leaflets is green, often with purplish dotted spots and pubescent on both sides. The margin is entire, more densely pubescent. The base is wedged and the top rounded, shortly mucronate. Venation consists of 4 to 8pairs of arched ribs
 
Inflorescence

The inflorescence consists of terminal or axillary racemes sometimes grouped into a leafy panicle, 15 to 30 cm long. The flowers are inserted in groups of 2 or more, supported by a pedicel of 8 to 15 mm long, at the base of which are closely oval primary bracts with attenuated summit, 3.5 to 6 mm long.
 
Flower

The flower is papilionaceous. The calyx of the flower is 3 to 4 mm, divided into rather short lobes, the inferior longer, finely pubescent with hooked hairs mixed with straight long sparse hairs. The corolla is usually pink or purple in color, at least on the margin, sometimes white, yellow or greenish, 4 to 6 mm long. The stamens are fused into a beam of 9 stamens forming a muff under the ovary, with 1 additional free stamen over the ovary.
 
Fruit

The fruit is a pod, 1 to 3 cm long ending in a short tip. It consists of 3 to 7 articles, indehiscent, elliptical to sub circular, 3 to 6.5 mm long and 3 to 4 mm wide, interconnected by a narrow median isthmus. Each article contains a seed. The pod is covered by a pubescence of hooked hairs. The pod becomes tortuous or winds up in spirals at maturity (hence the species name).
 
Seed

The seed is kidney-shaped to ellipsoid, 3 mm long and 2 mm wide. Seed coat smooth and shiny of brown to green.

https://www.gbif.org/species/2967221