Description from Flora of China
Annuals, biennials, or perennials. Leaves alternate, rarely opposite; blade ovate to broadly ovate, unlobed or pinnatifid, rarely sessile and cordate. Capitula in terminal, paniculiform cymes, radiate, rarely discoid; involucre flat to reflexed, rarely hemispheric; phyllaries persistent, in 1 or 2(or 3) series; receptacle conical to columnar; paleae scarious, conduplicate or concave, ± enclosing florets. Ray florets neuter; corolla golden to lemon-yellow, orange, or reddish, or bicolored. Disk florets: corolla yellow to purplish, often bicolored. Achenes oblong to obpyramidal, 4-angled, glabrous or with some thick, multicellular trichomes on radial angles; pappus a small crown of minute scales, or of 2-4 small scales, or absent.
Rudbeckia amplexicaulis Vahl, R. fulgida Aiton, R. fulgida var. speciosa (Wenderoth) Perdue, R. maxima Nuttall, and R. triloba Linnaeus are cultivated in China.
About 17 species: North America; two species (both introduced) in China.