Senna septemtrionalis, commonly known as arsenic bush,[2] is a species of flowering plant in the family Fabaceae and is native to Central America, the southern United States and Mexico, but is naturalised in many other countries.

Senna septemtrionalis is an erect, glabrous shrub that typically grows to a height of up to 3 m (9.8 ft).

[2][3] This species was first formally described in 1802 by Domenico Viviani who gave it the name Cassia septemtrionalis in Elenchus Plantarum Horti Botanici J.

Dinegro Observationibus quod Novas, vel Rariores Species Passim Interjectis.

[4][5] In 1982, Howard Samuel Irwin and Rupert Charles Barneby transferred the species to the genus Senna as S. septemtrionalis in the Memoirs of the New York Botanical Garden.