All species of the genus Manihot (Euphorbiaceae) are native in the New World tropics and are frost-sensitive. They are all rather sporadic in their distribution, never become dominant members of the local vegetation, and most are found in relatively dry regions. Manihot esculenta (Cassava) is a cultivated crop in most tropical areas. This treatment of Manihot and the related genus Manihotoides includes keys, descrptions, and photographic images.