Global description
Desmodium intortum is a creeping and ascending plant, often branched, reaching 1 to 2 m in height. The stem is trigonal, pubescent, covered with rigid hook hairs, clinging to the touch, often reddish brown. The leaves are alternate, compound, with three elliptical leaflets, pubescent on the 2 sides. Pink flowers, turning purple or white, are arranged on terminal and axillary inflorescences. The fruits are often curved pods, 2 to 3 cm long, with unequal elliptical articles and covered with small hooked hairs.
Cotyledons
The cotyledons are kidney-shaped, light green, shortly stalked. The lamina is 6 mm long and 3 mm wide.
First leaves
The first leaves are simple, alternate, light green, carried by a petiole, 12 to 15 mm long. The lamina is obovate, 8 mm long and 6 mm wide, with a clear central rib. The following leaves become trifoliate with two small lateral leaflets of 6 mm long and orbicularis terminal leaflet of 1.5 cm in diameter.
General habit
Prostrate growth habit, ascending to creeping, climbing on sugarcane. It measures 1 to 3 m long.
Underground system
The plant has a taproot system
Stem
The stem is trigonal, full, covered with stiff, curved, hooked hairs, rough to the touch.
Leaf
The leaves are alternate, composite, and trifoliate. They are carried by a petiole,1.5 to 7 cm long, pubescent. The stipules are narrowly ovate to acuminate, 3 to 10 mm long, deciduous. The leaflets are ovate to narrowly ovate, acute to acuminate at the top corner, 3 to 12 cm long and 1.5 to 7 cm wide. The base is rounded or truncated. The margin is entire. The two surfaces are pubescent, with arched venation. The top face is often reddish brown.
Inflorescence
The inflorescence consists of compact racemes, composed of many flowers. They are elongate, terminal or axillary, 10 to 30 cm long, non-leafy.
Flower
The flowers are solitary or in pairs. Primary bracts oval to acuminate, 4 to 10 mm long, deciduous. Calyx 4 to 5 mm long, with 5 lobes, the inferior lobe significantly longer, puberulous to sub-glabrous. The corolla is pink, turning purple or white, 9 to 10 mm long.
Fruit
The fruit is an articulated pod, 2 to 3 cm long, often curved, covered with dense hooked hairs. It consists of 3 to 10 unequally elliptical articles of 3 to 3.5 mm, rounded on both sides, with eccentric narrow articulations.
Seed
The seed is ellipsoid to reniform, 2 mm long.