Asclepias incarnata L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Erect, stout, to 1.5 m, branched above; lvs lanceolate to oblong or linear-oblong, usually acuminate, at base acutish to subcordate; umbels usually several or many; cor pink to red (white), the lobes 4.5–6 mm; hoods 2.5–3 mm, about equaling the gynostegium, the lateral margins entire, divergent from near the base; horn subulate, incurved, much surpassing the hood; 2n=22. Open swamps, ditches, and wet prairies; N.S. to Fla., w. to Sask., Utah, and N.M. June–Aug. Var. incarnata, with nearly the range of the sp., but not common in the Atlantic seaboard states, is sparsely and inconspicuously hairy to essentially glabrous, and the stems are usually repeatedly branched. Var. pulchra (Ehrh.) Pers. largely replacing var. incarnata in N.S., N. Engl., and the coastal states southward, is evidently hairy and seldom much branched, with mostly broader lvs more abruptly contracted at base.