It is a spreading shrub with pinnate leaves with five to seven pairs of broadly elliptic to egg-shaped leaflets, and groups of five to twelve yellow flowers arranged in dense groups of twenty to sixty on the ends of branches and in upper leaf axils.

Senna planitiicola is a spreading, glabrous shrub that typically grows to a height of 0.2–1.5 m (7.9 in – 4 ft 11.1 in).

[2][4][5][6] This species was first formally described in 1859 by Ferdinand von Mueller who gave it the name Cassia pleurocarpa in Fragmenta Phytographiae Australiae, from specimens collected by Augustus Oldfield near the Murchison River.

[7][8] In 1990, Barbara Rae Randell transferred the species to Senna as S. pleurocarpa in the Journal of the Adelaide Botanic Garden.

[3][4][5] Variety angustifolia is widespread in Western Australia, where it grows in subtropical to temperate, semi-arid areas of that state,[13][18] var.