Macroptilium lathyroides

Native to tropical and subtropical America, this annual or short-lived perennial herb has erect, trailing or twining stems. Its red to reddish-purple flowers have a spirally twisted keel. The long, slender pods split forcefully as they ripen, twisting their valves and scattering the seeds. The plant is grown as livestock forage and used as a green manure or cover crop because of its nitrogen fixation. It has become naturalized widely and is regarded as an environmental weed in Queensland and the Northern Territory of Australia. In Florida, it can form dense stands in coastal marshes and dunes. Photographed in the department of Atlantico, Colombia.