Biennials or short-lived monocarpic perennials, (50-)100-300(-400) cm; taproots and often a cluster of coarse fibrous roots, roots without tuberlike enlargements. Stems single, erect, villous with septate trichomes, sometimes ± glabrate, sometimes distally thinly tomentose; branches few-many, ascending. Leaves: blades oblanceolate to elliptic or ovate, 10-40 × 1-13 cm, margins flat, finely spiny-toothed and otherwise undivided to coarsely toothed or shallowly pinnatifid, lobes broadly triangular, main spines 1-5 mm, abaxial faces white-tomentose, adaxial faces green, glabrate to villous with septate trichomes; basal usually absent at flowering, winged-petiolate, bases tapered; principal cauline well distributed, gradually reduced, bases narrowed, sometimes weakly clasping; distal cauline well developed. Heads 1-many, in corymbiform or paniculiform arrays, (± elevated above principal cauline leaves. , not subtended by ring of spiny bracts. Peduncles 0-5 cm (leafy-bracted. . Involucres ovoid to broadly cylindric or campanulate, (2-)2.5-3.5(-4) × (1.5-)2-3(-4) cm, thinly arachnoid. Phyllaries in 10-20 series, strongly imbricate, greenish with subapical darker central zone, ovate (outer) to lanceolate (inner), abaxial faces with a narrow glutinous ridge (milky when fresh, dark when dry), outer and middle entire, bodies appressed, spines slender, abruptly spreading, 3-4 mm; apices of inner phyllaries spreading, narrow, flattened, entire, spines spreading, slender, 3-4 mm; apices of inner phyllaries spreading, narrow, flattened, ± dilated, ± erose or finely serrulate. Corollas pink to purple (white), 20-35 mm, tubes 10-16 mm, throats 5-12 mm, lobes 5-9 mm. Style tips 4-6 mm. Cypselae tan to dark brown, 4-5.5 mm, apical collars stramineous, 0.5-1 mm; pappi 12-24 mm. 2n = 18. Flowering summer-fall (Jun-Oct). Prairies, woodlands, disturbed sites, often in damp soil; 50-700 m; Ala., Ark., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.Y., N.C., N.Dak., Ohio, Okla., Pa., S.C., S.Dak., Tenn., Tex., W.Va., Wis.
Robust, fibrous-rooted perennial, 1-3(-4) m, openly branched when well developed; stem crisply spreading-hirsute to subglabrate, sometimes slightly tomentose in the infl; lvs large, the lower to 5 נ2 dm, broadly oblanceolate to obovate or elliptic, densely white- tomentose beneath, scabrous-hirsute to subglabrous above, merely spiny-toothed or coarsely toothed to sometimes lobed (seldom more than halfway to the midrib), the reduced ones of the infl sometimes more evidently lobed than the others; heads several or numerous on the ±leafy peduncles; invol (2-)2.5-3.5(-4) cm; middle and outer bracts tipped with a spine 2-5 mm; inner bracts merely attenuate or often with a scarious, slightly dilated and erose tip; fls mostly pink-purple; achenes 4.5-6 mm; 2n=18(20). Fields, waste places, river-bottoms, and open woods; Mass. to N.D., s. to Fla. and Tex. July-Oct. (C. iowense)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.