Perennials, 50-300 cm (rhizomes often elongate, slender, plants colonial, roots fibrous). Leaves green, blades broadly ovate to lanceolate, all but distalmost 1-2-pinnatifid or pinnately compound, leaflets/lobes 3-11, bases cuneate to attenuate or cordate, margins entire or dentate, apices acute to acuminate, faces glabrous or hairy (sometimes with translucent patches); basal (often withering before flowering) petiolate, 15-50 × 10-25 cm; cauline petiolate or sessile, mostly lobed to pinnatifid, sometimes not lobed, 8-40 × 3-20 cm. Heads (2-25) in loose, corymbiform arrays. Phyllaries to 2 cm (8-15, ovate to lanceolate, margins mostly ciliate, glabrous or hairy). Receptacles hemispheric or ovoid to globose; paleae 3-7 mm, apices (at least of proximal) truncate or rounded, abaxial tips densely hairy. Ray florets 8-12; laminae elliptic to oblanceolate, 15-50 × 4-14 mm, abaxially hairy. Discs 9-30 × 10-23 mm. Disc florets 150-300+; corollas yellow to yellowish green (lobes yellow), 3.5-5 mm; style branches 1-1.5 mm, apices acute to rounded. Cypselae 3-4.5 mm; pappi coroniform or of 4 scales, to 1.5 mm. Cultivars of Rudbeckia laciniata are grown as ornamentals. The cultivar `golden-glow´ is widely planted and occasionally escapes cultivation. Among the varieties traditionally recognized in floristic treatments, vars. ampla and heterophylla are the most distinctive. Detailed investigation may show that the other varieties, from eastern North America, represent broadly intergrading forms that should be subsumed under var. laciniata.
Perennial from a woody base, 5-30 cm; stem glabrous, often glaucous; lvs large, petiolate, coarsely toothed or laciniate, some or most of them pinnatifid or sometimes merely trilobed, subglabrous, or hairy beneath; disk yellow or grayish, 1-2 cm wide, hemispheric at first; rays drooping, lemon-yellow, 6-16, 3-6 cm; receptacular bracts blunt, distally viscidulous-canescent; pappus a short, usually toothed crown; 2n=36, 54, 72, 102+. Moist places; Que. to Fla., w. to Mont. and Ariz. July-Sept. Three vars. with us, a fourth cordilleran.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.