Stems viny, to 4 m, very sparsely short-pilose, sometimes nearly glabrous. Leaf blade mostly 1-2 pinnate, many leaves simple; primary leaflets 2-8 plus additional tendril-like terminal leaflet, deeply 2-5-lobed or unlobed or 3-foliolate, leaflets or major lobes lanceolate to broadly ovate, 1-11 × 1-6 cm, leathery (thin in var. pitcheri ), ± prominently reticulate adaxially; surfaces abaxially nearly glabrous to densely pubescent, not glaucous. Inflorescences axillary, 1-7-flowered. Flowers ovoid to urn-shaped; sepals pale to dark bluish or reddish purple, sometimes whitish toward tip, ovate-lanceolate, 1.2-3(-4) cm (larger sepals mostly in w part of range), margins narrowly expanded distally to about 1 mm wide, thin, crispate toward tip, tomentose, tips acuminate, recurved, abaxially sparsely to densely appressed-puberulent. Achenes: bodies appressed-pubescent; beak 1-3 cm, nearly glabrous to ± appressed-pubescent or silky. Clematis pitcheri is highly variable, notably in the size and thickness of the leaflets, the external sepal color and internal color of the recurved tips, and the amount of pubescence of the beaks. Additional varieties might be recognized, as some authors have done in the past, but the extent of intergradation and the lack of correlation among varying traits tend to make recognition of additional varieties impractical (W. M. Dennis 1976). The two varieties recognized here show very extensive intergradation in the western part of the range of the species. Although otherwise similar to Clemitis reticulata , C. pitcheri differs distinctly in its more coarsely reticulate leaves, with the smallest closed areoles mostly over 2 mm long, and its scarcely raised tertiary and quaternary veins.
Stems climbing or scrambling, generally somewhat hairy at least at the nodes; lfls usually 3-5 pairs, lance-ovate to cordate-ovate, entire to 2-3-lobed or even deeply parted, firm, prominently reticulate on both sides, subglabrous except for the generally somewhat hairy rachis- joints, or seldom evidently hairy beneath, not glaucous; cal urceolate; sep 1.2-2.5 cm, lance-ovate, acute or shortly acuminate, tomentose on the margins, minutely hairy or glabrate on the back; style at anthesis glabrous, at maturity 2-3 cm, firm, somewhat hairy below, essentially glabrous above the middle; 2n=16. Dry or moist woods; Ind. to Nebr., s. to Tenn., Ark., Tex., N.M., and ne. Mex. June-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.