Low rattlebox

Crotalaria pumila, commonly called low rattlebox or low rattlepod, is a low-growing annual or short-lived perennial herb of the Fabaceae reaching 10-50 cm in height. It is native to the southwestern United States, Mexico, Central America, and parts of South America, where it occurs on dry slopes, sandy soils, roadsides, and disturbed open ground from sea level to about 2400 m elevation. The stems are slender, branched, and finely pubescent; leaves are alternate and trifoliolate with small obovate to oblanceolate leaflets. Bright yellow papilionaceous flowers about 6-10 mm long are borne in short terminal racemes and are followed by characteristic inflated, oblong pods 1.5-2.5 cm long that turn dark brown or black at maturity, the loose seeds rattling within. Like many Crotalaria species, the plant contains pyrrolizidine alkaloids and is regarded as toxic to livestock.