Colobus or black-and-white colobuses (or colobi), is a genus of Old World monkeys of the Cercopithecidae family, native to Africa. They are closely related to the brown colobus monkeys of genus Piliocolobus. The word "colobus" comes from Greek κολοβός kolobós ("docked"), and is so named because in this genus, the thumb is a stump. Colobuses are herbivorous, eating leaves, fruit, flowers, and twigs. Their habitats include primary and secondary forests, riverine forests, and wooded grasslands; they are found more in higher-density logged forests than in other primary forests. Their ruminant-like digestive systems have enabled these leaf-eaters to occupy niches that are inaccessible to other primates.