Plant: perennial herb; stems erect, typically unbranched, 60-120(-150) cm tall, glabrous to rather glaucous; milky sap Leaves: irregularly alternate to approximate, sessile, the blades linear, 5-25 cm long, 1-8 mm broad, attenuate at apex and base, glabrous on both surfaces, or with a few hairs on the margins and midvein below INFLORESCENCE: UMBELS lateral in the upper portion of the stem, spreading-pubescent, 2-4 cm broad, sessile or the peduncles to 3.5 cm long Flowers: small; calyx lobes 3.5-5 mm long; corolla greenish or flushed with pale purple, the lobes 5-7 mm long; hoods sessile, curved-ascending, ovoid-oblong, 2.2-3 mm long, 0.9-1.5 mm broad in the middle, half to two-thirds as long as the gynostegium, truncate to retuse at the top, rounded-saccate at the base and with a pair of wing-like, rounded lobes spreading at right angles from the margins, the horns digitate, erect, attached near the middle of the hoods, ca. 1 mm long and scarcely exserted, or concealed within the hoods and variously reduced in length, or entirely absent and represented by a more or less distinct vertical ridge at the base of the back wall of the hoods; anther wings 2-2.4 mm long; corpusculum 0.6 mm long, the pollinia 1.2-1.3 mm long Fruit: FOLLICLES erect on deflexed pedicels, 7-12 cm long Misc: Creeks, canyons, open woodlands; 1050-2200 m (3500-7200 ft); Jun-Aug REFERENCES: Sundell, Eric. 1994. Asclepiadaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 169-187.

Sundell 1993, Woodson 1954, Kearney and Peebles 1969, Nabhan et al 2015

Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Herbaceous perennial, 60-120 cm tall; stems stout, erect, typically unbranched; herbage glabrous to glaucous; plants with milky sap. Leaves: Irregularly alternate to approximate (nearly opposite), sessile; the blades linear, 5-25 cm long, 1-8 mm broad, attenuate at apex and base, glabrous on both surfaces, or with a few hairs on the margins and midvein below. Flowers: Yellow-green, in pubescent lateral umbels, 2-4 cm broad, sessile or on peduncles to 3.5 cm, from several or many of the upper nodes; flowers small, 3-5 mm long; corolla greenish or flushed with pale purple, lobes 5-7 mm long; hoods sessile, curved-ascending, ovoid-oblong, 2 mm long, yellow; horns digitate, erect; sepals 3-5 mm long. Fruits: Follicles erect on deflexed pedicels, 7-12 mm long. Ecology: Found along creeks, in canyons and in open woodlands and on sandy slopes from 3,500-7,500 ft (1067-2286 m); flowers June-September. Distribution: From the Great Plains across to Arizona, through Texas and south into Coahuila. Notes: This is an erect milkweed that has clusters of stems with long, narrow leaves which are sometimes alternate and sometimes opposite, and showy clusters of yellow flowers emerging from the leaf axils. Very similar to Asclepias rusbyi, which is distinguished by the minute to well-developed hornlike crest on the inner face of the hoods; typical forms of the A. engelmanii do not have this appendage. This is a known monarch host plant. Ethnobotany: Used for nasal congestion from a cold. Etymology: Asclepias is named for the Greek god of healing Asklepios, while engelmanniana is named for George Engelmann (1809-1884), a German-American doctor and botanist who worked in the western US. Synonyms: Acerates auriculata, Asclepias auriculata Editor: SBuckley 2010, 2014, AHazelton 2015