Decumbent or ascending, 2-6 dm; lvs oblong, lance- oblong, or elliptic, 6-12 cm, rounded or obtuse, abruptly narrowed at base to a 4-10 mm petiole; cor greenish, rotate (the lobes spreading or with ascending tip, not reflexed), 2-3.5 cm wide; hoods violet or purple, 4-6 mm, the horn rudimentary, represented by a small, flat, median plate near the summit of the hood. Prairies, barrens, and dry upland woods; O. to Mo. and Nebr., s. to Fla. and Tex. May-June, sometimes also in late summer. (Asclepiodora v.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.