This is widespread in woodlands of eastern North America. It is usually distinct due to its long disc corolla lobes, which turn reddish-purple to brown; inflorescences usually have relatively long divaricate to ascending sub-racemiform branches, with heads somewhat secund on 0-1 cm peduncles; lower leaves are relatively broad, typically glabrous below except for hairy mid-veins; stems growi from woody caudices with relatively short rhizomes, usually arching up, and "more or less curly villous to glabrous" (Cr). However, lateriflorum is highly variable (2n = 16, 32, 48), and hybrids are known with several other species, sometimes making identification difficult (Semple et al. 2002; FNA 20, Y, W). Several colls. from Ky. have been referred to var. angustifolium (Wieg.) Nesom, var. hirsuticaule (DC.) Nesom, var. horizonatale (Desf.) Nesom (= A. pendulus Ait.), or var. tenuipes (Wieg.) Nesom, but these taxa have not been consistently recognized in recent treatments. In Ky. distinct plants with leaves that are relatively narrow and completely glabrous are known from streamheads and seeps in BELL, POWE, MARS, MCRE and elsewhere (EKY, KY, Univ. of Waterloo). The name var. tenuipes was apparently misapplied to such plants by F and others; they can probably be included within var. angustifolium, which is known mostly from more northeastern regions (Semple et al. 2002).