The genus Lasianthaea ranges from Arizona to Panama, however, all but two taxa are apparently restrictred to Mexico. Of the eleven species recognized in this treatment, seven are typically shrubs. The half-shrubby habit exhibited by several of the typically shrubby species may be an adaptation to local conditions. The other four species are typically perennial herbs (sometimes woody in age below), with perennating structures very close to or at ground level. Includes keys, descriptions, and distribution maps.