Macroptilium atropurpureum, commonly referred to as purple bush-bean, or siratro is a perennial legume recognized by its climbing dense green vines and deep purple flowers. The plant is indigenous to the tropical and subtropical regions of North, Central and South America, as far north as Texas in the USA and as far south as Peru and Brazil, but it can be found in many tropical regions around the world. Rich in protein, Macroptilium atropurpureum is commonly used for cattle pastures intercropped with grass, used in hay, or as a ground cover to prevent soil erosion and to improve soil quality.