Perennials, to 200 cm (rhizomatous, rhizomes stout). Stems densely hirsute (hairs mostly antrorse, to 0.5 mm). Leaves: blades ovate to elliptic (not lobed), margins denticulate to serrate, apices acute to obtuse or acuminate, faces densely hirsute and gland-dotted (glands fewer adaxially); basal 15-30 × 3-10 cm, bases attenuate; cauline petiolate, ovate to elliptic, proximal 3-25 × 1-15 cm, usually 3-5-lobed, bases truncate to cuneate or rounded. Heads (8-25) in loose, corymbiform to paniculiform arrays. Phyllaries to 1.5 cm (faces hairy and ± gland-dotted). Receptacles conic to hemispheric; paleae 4-6 mm, apices acute, abaxial tips hirsute and gland-dotted. Ray florets 10-16; laminae (yellow to yellow-orange) linear to oblanceolate, 20-40 × 5-8 mm, abaxially sparsely hairy, abundantly gland-dotted. Discs 10-17 × 5-15 mm. Disc florets 200-400+; corollas yellowish green on basal 1/2, otherwise brown-purple, 3-4.2 mm; style branches ca. 1 mm, apices acute. Cypselae 2-3.5 mm; pappi coroniform, to ca. 0.2 mm. 2n = 38. Flowering late summer-fall. Mesic to wet prairies, stream banks, and woodland openings; 20-300 m; Ark., Conn., Ill., Ind., Iowa, Kans., Ky., La., Mass., Mich., Miss., Mo., N.Y., N.C., Okla., Tenn., Tex., Wis. Rudbeckia subtomentosa is often cultivated as an ornamental.
Perennial from a stout rhizome; stem 6-20 dm, glabrous below, ±densely short-hairy above; lvs firm, densely short-hairy, especially beneath, ovate to sometimes lance-elliptic, petiolate, serrate, generally some of the larger ones deeply trilobed; disk dark purple or brown, 8-16 mm wide, not elongating; rays 12-21, yellow, 2-4 cm; receptacular bracts obtuse or acutish, distally viscidulous-canescent; pappus a minute crown; 2n=38. Prairies and low ground; Mich. to Wis., s. to w. Tenn., La., and Okla. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Infrequent in rather wet prairie habitats in the northwestern part of the state, mostly along roadsides; and in the southwestern part of the state in low, open woods, where it is usually associated with prairie plants.