Global Range: E. californica presently occurs from western Canada through Texas and in all states in between. Eastwards, it is found in a few plains states and in most states east of the Mississippi River (USDA-NRCS 1999).
Apparently, the native range of this species is the southwest U.S., as far east as Utah; occurrences further east are apparently escapes from cultivation, or resulting from "wildflower," roadside, or reclamation plantings (Nelson and Williams 1992, Welsh et al. 1993, Weber and Wittmann 1996a, Gleason and Cronquist 1963).
Subspecies mexicana is apparently native to west Texas (Correll and Johnston 1970), westcentral and southwestern New Mexico (Martin and Hutchins 1980), all but the northeastern portion of Arizona (Kearney and Peebles 1960), northern Sonora (Kearney and Peebles 1960), extreme southwest Utah (Albee et al. 1988), along the Colorado River corridor into far southern Nevada (Nevada Natural Heritage Program, Kartesz 1988), and desert mountains of California (Hickman 1993). Kartesz (1999) considers it extant in all these states.
Hickman (1993) lists the range of subspecies californica as California to southern Washington, Nevada [western], New Mexico, and northwest Baja California, although the western Nevada occurrences may have spread from plantings (Nevada Natural Heritage Program). It has apparently spread from cultivation throughout much of the eastern and western United States and Canada (Kartesz 1999). It is reportedly introduced and non-native to Illinois, Michigan, British Columbia, Manitoba, Wyoming, Ontario, Tennessee, and Missouri (Natural Heritage Programs).
An attempted introduction of this species was purportedly made in the Franklin Mountains near El Paso, Texas, but the plant failed to persist at this location (Bill Carr pers. comm.).