Perennials. Stems pilosulous to villous and/or stipitate-glandular. Leaves: petioles 3-8(-12+) cm, sometimes raggedly winged; blades 4-20(-40+) × 2-12(-25+) cm, larger usually deeply pinnately lobed, lobes 5-7. Cypselae 3-4 mm, 3-angled or -ribbed. 2n = 30. Flowering May-Aug(-Oct). Damp, shaded sites, calcareous soils; 100-1000 m; Ont.; Ala., Ark., Conn., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., Mich., Minn., Mo., N.Y., N.C., Ohio, Okla., Pa., Tenn., Vt., Va., W.Va., Wis.
From Flora of Indiana (1940) by Charles C. Deam
This species is found, no doubt, in every county except possibly in a few of the prairie counties. It is strictly a woodland species and prefers a moist soil covered with leaf mold in thick woodland. It is rarely found on steep slopes without leaf mold or in open woodland, but is often found in overflow land along streams. [In forma radiata] the ligules of the heads are fully developed, usually being about 1 cm long. Found with the species but rare.
Coarse perennial 0.6-2 m, glabrate below, viscid-villous or stipitate-glandular above; lvs large, thin, to 3 dm, broadly oblong to ovate, pinnately few-lobed, also toothed, the petiole wingless or winged only near the blade; heads in congested cymes ending the branches, the pale yellow disk 6-13 mm wide; invol bracts lanceolate to lance-linear, narrower and often shorter than the bracts that subtend the ray-achenes; cor of pistillate fls minute and tubular, or expanded into a short, whitish ray to 10(-15) mm; achenes 3-4 mm, unequally 3-ribbed and -angled, not striate; 2n=30. Moist woods, especially in calcareous regions; Vt. and Ont. to Minn., s. to Ga. and Ark. June-Oct. (P. radiata, the radiate form)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.