Plant: perennial herb; stems erect, unbranched, 50-180 cm tall, densely short wooly when young, soon glabrate; milky sap Leaves: opposite, sessile or the petioles to 2 mm, the blades broadly lanceolate to mostly ovate, 4-25 cm long, 3-11 cm broad, rounded to shallowly cordate and more or less clasping at the base, attenuate to an acute apex, densely short woolly when young, in age more or less glabrate on both surfaces, the margins erose INFLORESCENCE: UMBELS lateral to subterminal at the upper nodes, 5-8 cm broad, the peduncles 2-13 cm long, the pedicels wooly Flowers: large; calyx lobes ca. 3-4 mm long; corolla greenish, the lobes 6-9 mm long; hoods greenish white to yellow-brown, erect-ascending, obovoid-triangular, widening upward to a truncate apex, 3.5-5 mm long along the dorsal surface, 2.5-5 mm broad at the top, about as long as the gynostegium, the horns radially flat, attached to about the middle of the hoods, sickle-shaped, exserted ca. 2 mm to the center of the stigma head; anther wings 2-2.8 mm long; corpusculum ca. 0.4 mm long, the pollinia 1.4-1.5 mm long Fruit: follicles erect on deflexed pedicels, 7-9 cm long Misc: Washes and roadsides in desert scrub communities; 50-1500 m (200-5000 ft); Apr-Oct REFERENCES: Sundell, Eric. 1994. Asclepiadaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 169-187.

Nabhan et al 2015

Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: This robust herb produces several stems to 1.5 m, from a thick fleshy taproot. Leaves: Thick, nearly succulent, wooly white leaves become hairless with age; narrowly lanceolate or broadly ovate in shape. Its leaves are remarkably large for a perennial plant in the extremely arid portions of the Sonoran Desert. Flowers: Green petals with white hollow-cheeked hoods resembling corn kernels that yellow with age; fragrant. Ecology: Found in washes and roadsides in Sonoran and Mohave Desert scrub, especially on sandy plains and hummocks on either side of the Lower Colorado River, from 200 to 5,000 ft (61-1524 m); flowers in late spring and early summer, occasionally in other seasons Distribution: southern Nevada and Utah in the north, to southeastern California, Baja California, southwestern Arizona, and Sonora in the south. Notes: Its pale greenish, somewhat hairy flowers, are visited by hairstreak butterflies, pepsis wasps, orange and black spider wasps, and yellow-banded tiphiid wasps. Orange and black milkweed bugs (Oncopeltus fasciatus) suck moisture from its unripe fruits. This is a known monarch host plant. Synonyms: Asclepias demissa, Asclepias leucophylla, Asclepias obtusata, Asclepias rothrockii Editor: AHazelton 2015