A coarse, upright, much-branched perennial that can cover entire valleys. Flowerheads bright yellow, to 1½ inches wide, bracts often purple-tipped. Ray flower corollas about 1/2 to 3/8 inch long. Blooms June–October. Leaves hairy (as are the stems), alternate, sessile, often with a few fine, sharp teeth, to 3 inches long, elliptical to lanceolate, with pointed tips.
Similar species: Of the 2 other Heterotheca spp. in Missouri, only camphorweed, or telegraph plant (H. subaxillaris), is likely to be encountered. It’s mostly in the Bootheel and along the Missouri and Mississippi rivers; the corollas of its ray flowers are shorter, about 1/4 to 3/8 inch long. Soft goldenaster (Bradburia pilosa) is closely related. It is annual, rarely more than 2 feet tall, has flowerheads less than 1 inch wide, and is found in the southern third of Missouri.