Arrowhead rattlebox

Crotalaria sagittalis, commonly known as arrowhead rattlebox or arrow crotalaria, is an annual or short-lived perennial herb in the legume family Fabaceae native to the eastern and central United States, Mexico, and parts of Central and South America. It typically grows 10 to 40 cm tall on slender, hairy, erect or ascending stems. The leaves are simple, lanceolate to oblong, hairy on both surfaces, with distinctive arrowhead-shaped (sagittate) stipules that decurrent down the stem and give the species its epithet. Pea-like yellow flowers are borne in short few-flowered racemes from early summer through early autumn. The fruit is an inflated, oblong pod that turns brown to black at maturity; the loose seeds rattle within when shaken, which is the source of the name rattlebox. The plant favors dry sandy soils in fields, prairies and open woodlands. Like many Crotalaria species, it contains pyrrolizidine alkaloids and is toxic to livestock.