Senna was first used as medicine by the Arabians, and the leaves of this species are regularly gathered in this country, and used as a substitute for the imported. The nearly smooth, light green, slightly branched stalk grows from three to eight feet high, from a perennial root. From twelve to twenty oblong or lance shaped leaflets set in opposite pairs, on a slender stem from the large compound leaf. The base of the stem is guarded with a slender, club-shaped gland. The toothless leaflets are rather yellowish green in colour, and lighter on the under side. They have a fine, smooth surface, and are firm-textured. They are blunt or rounded at the apex, and are tipped with a tiny point, which terminates the midrib. They are somewhat sensitive when touched, and droop when roughly handled. The numerous, loosely constructed short-stemmed, golden-yellow flowers are clustered in the axils of the upper leaves. They are very showy, and three of the five curved petals are set upright and near together, while the other two spread downward. Ten unequal, dark brown capped stamens are of the same colour as the petals, and, together with the prominent yellowish green calyx, add greatly to the attractiveness of the blossom. The species is common in swamps and wet soil, often along roadsides, during July and August, from New England to Florida, and west to Michigan, Nebraska, and Louisiana.