Stems viny, to 5 m, glabrous or sparsely pubescent. Leaf blade 1-pinnate; leaflets 8-10 plus additional tendril-like terminal leaflet, elliptic to ovate, usually unlobed, occasionally 2-3-lobed, 2-8 × 1.5-6.5 cm, leathery, abaxially and adaxially prominently reticulate; surfaces abaxially glabrous and glaucous. Inflorescences axillary, 1-7-flowered. Flowers broadly urn-shaped; sepals abaxially pale lavender to reddish purple, grading to pale green toward tip, narrowly ovate, 1.5-3 cm, margins not expanded, thick, not crispate, tomentose, tips acute, slightly spreading, glabrous. Achenes: bodies appressed-pubescent; beak (3-)5-6 cm, plumose. 2 n = 16. Flowering spring-summer (Jun-Aug). Calcareous outcrops, sandy soils, dry woods and thickets, barrens, and roadsides; 30-100 m; Ala., Ark., Ky., Mo., Okla., Tenn., Tex.
Stems climbing; herbage glabrous, glaucous; lfls mostly 4 pairs, firm, strongly reticulate on both sides, ovate-oblong to cordate-ovate, often 2-3-lobed; cal urceolate; sep ovate-oblong, 1.5-2.5 cm, short-acuminate, bluish-lavender to reddish-purple, or whitish distally, densely tomentose on the margins, otherwise glabrous; style at anthesis densely hairy, at maturity 4-5 cm, densely long-plumose throughout; 2n=16. Dry, calcareous woods; chiefly Ozarkian, from s. Mo., Okla., and Ark. to Ky. and Tenn. June, July.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.