Prosopis nigra (synonym Prosopis algarrobilla) is a South American leguminous tree species that inhabits the Gran Chaco ecoregion (in particular, the transition zone between the Wet Chaco and the Southern Chaco), in Argentina and Paraguay. It is known as algarrobo negro in Spanish, which means "black carob tree" (the Spanish settlers gave it that name, as they did with many other species of genus Prosopis, because of its similarity to the European carob tree). It is also variously called algarrobo dulce, algarrobo morado and algarrobo amarillo ("sweet", "purple" and "yellow" carob tree, respectively).