Simple, erect or sometimes decumbent, 3-8 dm, with 2-5 pairs of lvs and a single (rarely 2) long-peduncled terminal umbel; lvs oval or broadly oblong, 7-15 cm, obtuse or rounded at summit, broadly rounded or commonly cordate at the sessile or subsessile base; peduncle 1-3 dm; umbel large, usually many-fld; cor greenish-purple, its lobes 8-11 mm; hoods pink, 5 mm, about equaling the gynostegium, the lateral margins adjacent, the broad summit truncate, entire or with a few low obtuse lobes; horns subulate, much exsert; fr 10-13 cm, erect on deflexed pedicels. Dry fields, prairies, and open woods, usually in sandy soil; N.H. to se. Minn., s. to Fla., Neb., and Tex. June-Aug. A. ةntermedia Vail is the hybrid with no. 7 [Asclepias syriaca L.].
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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