Oryza longistaminata is a perennial species of grass from the same genus as cultivated rice (O. sativa). It is native to most of sub-Saharan Africa and Madagascar. It has been introduced into the USA, and is often regarded as a (noxious) weed. Its common names are Longstamen Rice and Red Rice. Host resistance gene, Xa21, from O. longistaminata has been integrated into the genome of O. sativa as it confers broad resistance to rice blight disease caused by Xanthomonas oryzae pv. oryzae.