In the present work the two species of the genus prosopis native in the State of Rio Grande do Sul are described: Prosopis algarobilla Gris. and Prosopis nigra. (Gray) Hieron. The first of these is popularly known by inhanduvá and the second by algarrobo. The South American botanical literature only cites P. algarobilla for the state. The present work adds Prosopis nigra to the native flora of Rio Grande do Sul
