Chamaecrista mimosoides (L.) Greene

The genus Cassia was splited in Cassia, Chamaecrista and Senna, according to the following criteria :
 

Glands on the rachis and petiole	Petals	Stamens	Fruit	Bracteoles	Genus
absent	subequal	10	indehiscent	present	Cassia
absent or present	subequal	10 or 7 fertil	indehiscent or dehiscent not elastic, valve not coiling	absent	Senna
present	unequal	10 or5 fertil	elastically dehiscent, valves coiling	present	Chamaecrista

Distribution of Cassia spp. in the following table :

Global description

Chamaecrista mimosoides is an herbaceous plant, usually erect, sometimes prostrate, annual or perennial, which measures 30 cm to 1 m high. The more or less pubescent stem is of cylindrical cross-section and has a central pith. The leaves are alternate, compound paripinnate, distichous, stipulate with numerous linear leaflets (up to 140) whose size decreases from its base to its apex. The yellow flowers are axillary to supra-axillary, isolated or grouped in small inflorescences. The fruit is a flat narrow pod, straight and pubescent. The rhomboid-shaped seed is smooth and shiny, punctuated or mottled with yellow.
 
Cotyledons

The cotyledons are sessile, elliptic to oblong, abruptly rounded at the top. The main vein is visible; two other ribs from the attachment point are less visible.
 
First leaves

The first leaves are alternate and compound. The petiole is short, framed by stipules. The number of leaflets is lower than the mature leaves: 7 to 10 Pairs. The rachis and the margin of the lamina are bristled with stiff hairs that measure 0.5 to 1 mm.
 
General habit

Herbaceous, sub lignified, erect plant, sometimes prostrate, annual or perennial, which measures 30 cm to 1 m high.
 
Underground system

The plant has a taproot system
 
Stem

The stem that varies from fine to robust, is woody at the base. It has a cylindrical section, with a central pith. It is variably pubescent, glabrescent to covered with a crisped pubescent that is sometimes limited to a simple band. The pubescence is made of short, arcuate hairs.
 
Leaf

The leaves are paripinnately compound, alternate and distichous, narrow, 10 cm long and 1.5 cm wide. The petiole, 2 to 3 m long, is cylindrical, pubescent. It carries a cup-shaped gland at its apex. Its base is framed by 2 linear, triangular, erect stipules. The rachis is 4 to 10 cm long. It is of triangular section with scalloped ciliated upper ridge, and pubescent on the underside. It has numerous pairs of small leaflets, 25-70 pairs, the size of which gradually decreases from the base to the apex. The leaflets are linear-oblong, uninervate, 3 to 7 mm long and 0.6 to 1.3 mm wide, asymmetrical base, obtuse and mucronate apex. They are glabrous, with ciliated margin.
 
Inflorescence

The flowers are inserted above the axil of the petiole, isolated or grouped in beams of 2 to 4.
 
Flower

The slender flower stalk measures 4 to 20 mm long. Papillonaeous flowers are yellow in color with long petals, 5 to 7 mm.
 
Fruit

The fruit is a flat pod, straight or slightly curved, pubescent, 2.5 to 6.5 cm long and 2.5 to 5 mm wide. It is dark brown in color. It contains 12 to 24 seeds.
 
Seed

The seed is 3 mm long and 2 mm wide. It is rhomboid in shape with a  transverse rhombic cross section. Its surface is smooth and shiny, yellowish in colour, mottled and dotted.

https://www.gbif.org/species/2949769