Calopogonium mucunoides

Native from Mexico through the tropical Americas, this vigorous, short-lived perennial herb creeps, trails, or climbs by twining. Rust-colored hairs cover its stems, and each leaf has three broad leaflets. Blue to purple pea-shaped flowers are followed by hairy pods containing three to eight seeds. It is grown as a cover crop and green manure, protecting soil from erosion and suppressing weeds. Root bacteria fix nitrogen, helping improve soil fertility. Livestock generally find it less palatable than other forage legumes. It has invaded tropical ecosystems in northern Australia and is a weed in the Philippines, Malaysia, and Indonesia. Photographed in Colombia.