Crotalaria spectabilis

Native from the Indian subcontinent to Taiwan, this plant is an upright herb usually grown as an annual. It has been introduced widely outside Asia, including in tropical Africa, the Americas and Pacific islands, and is naturalized in Australia. It reaches about five feet tall, with simple, alternate leaves that broaden toward their tips and have hairy undersides. Long terminal clusters carry bright yellow pea-shaped flowers, sometimes marked with dark red-purple veins at the base of the broad banner petal. Inflated pods become dark as they mature, and loose seeds rattle inside the dry shells. The species has been used as a nitrogen-fixing cover crop but can become an aggressive agricultural weed. All parts are toxic to livestock, including dried plants in hay; the seeds are especially poisonous. Photographed in Colombia.