Asclepias albicans
Chuckwalla Mts.,, CA
Spjut 15737, Mar 2004

Asclepias eriocarpa
Kern Co., CA
Spjut 15737, Mar 2004

Asclepias erosa
29 Palms, CA
Spjut 16149, 12 Oct 2007

Asclepias curassavica

Asclepias eriocarpa

Asclepias subulata

Asclepias vestita
Los Angeles Co., W Mojave Desert
near Palmdale, CA

Asclepias albicans—epacunin, a sesquiterpene active in WA and PS (T/C 135), was isolated by Kupchan (Hartwell 1976).

Kupchan S. M., J. R. Knox, J. E. Kelsey, and J. A. Saenzrenauld.  1964.  Calotropin, a cytotoxic principle isolated from Asclepias curassavica L. Science 146: 1685–1686 (also noted in Hartwell 1976).

Koike K., C. Bevelle, S. K. Talapatra, G. A. Cordell and N. R. Farnsworth. 1980. Potential anticancer agents. V. Cardiac glycosides of Asclepias albicans (Asclepiadaceae).
Chem. Pharm. Bull. (Tokyo) 28(2): 401–405.