Stems taller, more slender than preceding species, 50--80 cm diam. 2n = 36.
Flowering spring. Native to desert washes where underground water is continuously available, naturalized in disturbed areas with moderate rainfall; introduced; Calif., Fla.; Mexico (native to Baja California Sur and Sonora).
The name Washingtonia filifera var. robusta (H. Wendland) Parish is nomenclaturally a synonym of W. robusta, although it was applied by S. B. Parish to palms now known as W. filifera. Hence, Parish's variety has been included erroneously by L. H. Bailey (1936) and others in synonymy under W. filifera.
Washingtonia robusta is widely cultivated in warm areas in the United States and has occasionally naturalized in Florida (S. Zona 1997) and southern California (J. W. Cornett 1986).