LEAVES: ovate to broadly lanceolate, to 3-4 times as long as broad, the bases cordate, the petioles mostly 1-4 cm long; flowers predominantly white; follicles mostly 6-8 cm long. NOTES: See also parent taxon for more description. Flood plains, canyons, disturbed sites, nc to se AZ: Cochise, Coconino, Graham, Pima, Pinal, Santa Cruz, Yavapai cos.; 750-1200 m (2400-4000 ft); Jul-Nov; NM, OK, TX; n Mex. REFERENCES: Sundell, Eric. 1994. Asclepiadaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 169-187.