LEAVES: blades lanceolate, linear-Ianceolate or narrowly oblong, apically acute.

NOTES: See also parent taxon. Chaparral, ponderosa pine, and riparian woodlands, meadows, roadsides; n & e AZ: Apache, Cochise, Coconino, Gila, Graham, Greenlee, Mohave, Navajo, Pima, Santa Cruz, Yavapai cos; 900-2450 m (3000-8000 ft); May-Sep; s Ontario; NH s to FL, w to MN, SD, UT, AZ; n Mex. Subsp. interior of c and sw N. Amer. is distinguished by its narrow leaves with obtuse to truncate bases.

REFERENCES: Sundell, Eric. 1994. Asclepiadaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 169-187.