Senna planitiicola, commonly known as yellow pea, arsenic bush, ant bush or pepper-leaf senna, is a species of flowering plant in the family Fabaceae and is endemic to northern Australia. It is an erect shrub with pinnate leaves with five to seven pairs of broadly elliptic to egg-shaped leaflets, and groups of three to eight yellow flowers on the ends of branches and in upper leaf axils.
Description Senna planitiicola is an erect shrub that typically grows to a height of up to , and is more or less glabrous. Its leaves are pinnate, long with five to seven pairs of broadly elliptic to egg-shaped leaflets, long and wide, spaced apart. There is a single, sessile gland above the base of the petiole. The flowers are yellow and arranged in groups of three to eight on the ends of branches and in upper leaf axils on a peduncle long, each flower on a pedicel long. The petals are up to long and there are six fertile stamens, the anthers long, as well as four staminodes. Flowering occurs in most months, and the fruit is a cylindrical pod long and wide.
Taxonomy This species was first formally described in 1926 by Karel Domin who gave it the name Cassia planitiicola in Bibliotheca Botanica. In 1988, Barbara Rae Randell transferred the species to Senna as S. planitiicola in the Journal of the Adelaide Botanic Garden. The specific epithet (planitiicola) means "inhabitant of level ground".
Distribution and habitat Senna planitiicola grows in a variety of soils and is widely distributed in north-western Western Australia, in arid parts of the Northern Territory, in northern South Australia and in northern Queensland.
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