Plants 6-10(-15) dm. Stems puberulent to ± tomentose. Leaves mostly cauline; blades elliptic to lance-ovate or lanceolate, 8-15(-18+) cm × 20-45(-75+) mm, l/w = 2-5, abaxially usually puberulent to tomentose or pannose (hairs ± erect, ± curled), seldom glabrate, resin-gland-dotted, adaxially scabrellous, glabrescent, not resin-gland-dotted. Heads in corymbiform-scorpioid arrays. Peduncles 1-25 mm. Involucres broadly campanulate to hemispheric, 4-6(-8+) × 4-7+ mm. Phyllaries 45-65+ in 5-6 series, usually puberulent (often resin-gland-dotted distally), sometimes glabrescent, margins ciliolate, the outer lance-ovate, 1-2 mm, inner oblong to lanceolate, 5-8+ mm, tips rounded-apiculate to acute (sometimes recurved). Florets (15-)20-25(-35+). Cypselae 2.5-3 mm; pappi fuscous to purplish, outer scales 25-30, 0.2-1 mm, contrasting with 35-40+, 5-7+ mm inner bristles. 2n = 34.
Regarding Vernona baldwinii and V. interior, L. H. Shinners (1950) wrote, 'The tips of the phyllaries vary from loosely appressed to squarrose, and from puberulent to almost completely glabrous on the inner face. The geographic distribution of the two extremes is nearly identical. I consider the two to be merely forms of one species.' I concur.
Stems 6-15 dm, thinly pubescent to commonly tomentose; lvs lance-ovate to ovate, 7-17 נ2-6 cm, acute or shortly acuminate, sharply serrate, puberulent above, tomentose beneath, with long, crooked hairs; infl 1-2 dm wide, flattened or irregular; heads mostly very numerous; fls 17-34; invol 5-8 mm, its principal bracts lanceolate or lance-ovate, acuminate, arachnoid- ciliate, densely resinous toward the tip on both sides of the prominent (often keeled) midvein; pappus rather light brown or brownish-purple; 2n=34. Dry prairies, plains, and upland woods. The Ozarkian var. baldwinii, occurring from w. Ill. to Mo., Ark., and e. Okla., has mostly 23-34 fls; the tips of the invol bracts are recurved, those of the inner pubescent on the inner surface. The var. interior (Small) Schubert, mainly on the Great Plains from s. Io. and Nebr. to e. Colo. and s. Tex., often weedy, has mostly 17-27 fls; the tips of the invol bracts are merely loosely spreading, not pubescent within. (V. interior)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.