Biennials, 20-350 cm; taprooted. Stems usually single, erect, glabrous or villous with septate trichomes; branches few-many, ascending. Leaves: blades narrowly to broadly elliptic, (10-)15-60 × (2-)5-15 cm, thin, ± flexible, deeply pinnatifid, lobes narrow, spreading, coarsely dentate or lobed, main spines 2-5 mm, abaxial faces thinly tomentose but often wholly glabrate in age, adaxial glabrous or sparsely villous with septate trichomes; basal often absent at flowering, petioles slender, winged, bases tapered; principal cauline becoming sessile and gradually reduced distally, bases spiny-lobed, sometimes decurrent; distal reduced to linear bracts. Heads few-many, in open corymbiform or paniculiform arrays. Peduncles 1-15 cm, essentially naked (not overtopped by crowded distal leaves. . Involucres hemispheric to campanulate, 1.5-2.5 × 1-2.5 cm, thinly arachnoid or glabrate. Phyllaries in 6-10 series, strongly imbricate, green or brownish, ovate or elliptic (outer) to linear-lanceolate (inner), abaxial faces with narrow glutinous ridge; outer and middle appressed, bodies entire, spines abruptly spreading, slender, 1-2(-3. mm; apices of inner often flexuous, flat, attenuate. Corollas white to pink, lavender, or purple, 17-25 mm, tubes 5-11 mm, throats 4-7 mm (noticeably wider than tubes. , lobes 5-7 mm; style tips 3-4.5 mm. Cypselae dark brown, 3-4 mm, apical collars stramineous, 0.5 mm; pappi 17-21 mm (longer bristles shorter than corollas). 2n = 24, 26, 28. Flowering summer (Jun-Aug). Roadsides, ditches, woodlands, usually in damp soil; 0-100 m; Ala., Fla., Ga., La., Miss., N.C., S.C., Tex., Va. Cirsium nuttallii occurs on the southern coastal plain from southeastern Virginia to southern Florida and west to eastern Louisiana.
Coarse biennial (1-)1.5-3.5 m, branching and many- headed when well developed, the heads commonly solitary at the ends of long, slender, subnaked branches; stem glabrous or with crisp spreading hairs; lvs arachnoid-tomentose beneath when young, generally eventually glabrate, smooth or somewhat crisp-hairy on the upper surface, thin, deeply pinnatifid, the lobes generally again toothed or cleft; larger (lower) lvs to 6 נ1.5 dm, but often soon deciduous; invol 1.5-2.5 cm, the middle and outer bracts with a glutinous dorsal ridge and tipped with a weak, abruptly spreading spine mostly 1-2(-3) mm, the inner bracts innocuous and merely attenuate, often crisped but not expanded; fls pink or lavender (often very pale) to white; achenes 3-4 mm; 2n=24, 28. Wet or dry, usually sandy soil, often in thickets; se. Va.; S.C. to Fla. and La. June-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.