This is a variable species (2n = 32 to 64), widespread along eutrophic streams across eastern North America. Treatments have differed greatly (e.g. Sm versus Correll & Johnston, 1970), and the species needs further revision in Ky., following J.C. Semple (FNA 20; Semple et al. 2002) and others (Y, W). S. lanceolatum usually occurs in dense stands with erect stems on distinctly long rhizomes, ascending paniculate branches, and heads usually on 0.5-5 cm peduncles (rarely secund). New shoots are produced only at distance from stem bases, as in ontarione and dumosum but not lateriflorum or pilosum. S. lanceolatum can rarely hybridize with several other species, including lateriflorum, ontarione and racemosum. It is often confused with ontarione without flowers, but leaf blades are usually more elongated at mid-stem (L/W mostly 5-10 versus 3-5), less deeply serrate, and mostly glabrous (versus softly short-hairy at least on distal leaves). Many Ky. plants were previously known as "Aster simplex Lam." or A. lanceolatus var. simplex (Willd.) A.G. Jones, but the type of simplex suggests a hybrid with lateriflorum (Cr). Most plants in Ky. and Tenn. (Ch) may be referable to the widespread southeastern var. latifolium (Semple & Chmiel.) Nesom, which has relatively large heads and broad leaves (2n = 64). The upper midwestern var. interior (Wieg.) Nesom, with relatively small heads (2n = 48, 64), has been reported from BULL (Gunn 1968), CARL (Mohlenbrock et al. 1966), ESTI (Anderson 1947), and elsewhere, but colls. have not been verified. The more northern var. lanceolatum (including A. simplex var. ramosissimus (Torr. & Gray) Cronq.), with relatively narrow leaves (2n = 48, 56, 64) has not been confirmed in the state.