Plants unarmed trees, shrubs, or herbs. Leaves imparipinnate, often with globose to clavate or cylindrical glands on the petiole or the rachis. Flowers in few- to many-flowered racemes, without bracteoles; sepals 5, the lobes overlapping; petals 5, yellow; stamens usually 10, their filaments straight, from shorter to not more than twice as long as the basifixed anthers; anthers dehiscent by terminal pores or short slits. Pods teret or compressed, indehiscent or more or less tardily dehiscent, valves not twisting. Seeds more or less compressed, often with a closed areole on each face.
Senna comprises about 240 species and is pantropical, but most abundant in the New World.
Unarmed trees, shrubs, or herbs with pinnately compound leaves having an even number of leaflets and yellow flowers with 10 stamens with straight filaments that are usually shorter than, and never more than twice as long as, the anthers. The pods may be terete or flat but are never twisted.
There are ~240 species. Most are tropical species but some species extend into temperate regions. Most of the species are native to the western hemisphere but there are many native in tropical regions of the eastern hemisphere.