Desmodium triflorum (L.) DC.

Global description

Desmodium triflorum is an annual to perennial species with creeping, hairy stems, rooting easily at the nodes. The leaves are alternate, compound, trifoliolate, with oblique stipules at the base of the petiole. The leaflets are obovate, emarginated at the top, pubescent on the lower face. The inflorescences are axillary carrying 2 to 5 flowers in fascicles, of papillionnaceous type and of pink to purple color. The fruit is a curved pod with a straight upper edge and a lower edge barely indented between the articles, bearing small oncinate hairs especially on the edges.

General habit

Desmodium triflorum is a sarmentose plant with creeping stems spread out on the ground. It can measure 40 cm length.

Underground system

The main root is a taproot. Adventitious roots, develop easily at the level of the nodes of the stem in contact with the ground.

Stem

The stem is cylindrical and solid, sometimes sublinear at the base, often tinted of purple. It is spindly, sarmentose and creeping, spread out on the ground. It is quickly and abundantly branched in a distical way (on a plane). It measures up to 40 cm length. It is covered with an abundant pilosity of long straight hairs, shaggy, white or brown-yellowish.

Leaves

The leaves are alternate, compound and trifoliolate. They are carried by a 5 mm long petiole at the base of which are 2 oblique, triangular stipules of 3,5 to 6 mm long and 1 to 1,5 mm wide, of reddish-brown color and multi-nerved. The rachis is 1 to 5 mm long. The leaflets are very short-stalked (0.5 to 1 mm), with two small linear stipels bearing white hairs at the base of the petiole. The leaflet blade is broadly obovate, emarginate at the apex usually short mucronate and wedge-shaped at the base, 3 to 14 mm long and 3 to 12 mm wide. The margin is entire, the upper face glabrous, and the lower face more or less pubescent with scattered recumbent white hairs with strongly reticulate venation. Leaflets with lateral veins in arcs not reaching the margin.

Inflorescence

The flowers are grouped in small fascicles of 2 to 5 flowers, carried by a long pedicel of 5 to 10 mm long, covered by long white hairs. The fascicles of flowers are arranged opposite to the leaf.

Flower

The flower of papillionaceous type, is subtended by 2 lanceolate bracts, hairy of 2 to 3,5 mm length and 1 to 1,5 mm broad. The calyx is formed by a short tube of 0,8 mm and 5 lanceolate lobes from 1 to 1,5 mm long, covered with long white hairs. The corolla of color pink to purple, sometimes white to yellow, is provided with a very rounded bilobed standard from 3 to 5 mm in diameter. Stamens in bundle, with welded nets until half height.

Fruit

The fruit is an arched, indehiscent pod, 6 to 18 mm long, with 3 to 5 articles 3 to 4 mm long and 2.5 to 3 mm wide, with a straight upper edge and a lower edge slightly indented at the joint between the articles. The faces are reticulated and covered with small hooked hairs.

Seed

Seeds are kidney-shaped, 1.7 to 2 mm long and 1.2 to 1.3 mm wide, brown with black speckles. The hilum is slightly eccentric.

Origin

Desmodium triflorum is native to all tropical regions of the Americas, Africa and Asia.

Worldwide distribution

This species was introduced in tropical Australia.

https://www.gbif.org/fr/species/10833216