Annual, 3–15 in. high; stem simple or branching at the base, divided at the top into an umbel of 3–5 rays, with or without 1 or more rays in the axils of the upper stem-leaves, thinly pilose with long fine hairs, sometimes almost glabrous. Leaves alternate, sessile, lanceolate, oblong-lanceolate, obovate or cuneately oblanceolate, acute or obtuse, sharply serrate, thinly pilose on one or both sides (at least along the midrib) to nearly glabrous. Stipules none. Rays of the umbel 2 1/2–5 in. long, cymosely 2–4 times divided. Bracts opposite or 3 in a whorl, sessile, ovate, usually acute, broadly rounded to subcordate at the base, serrate, glabrous on both sides or slightly pilose at the very base. Involucre solitary, sessile or subsessile, about 1 1/4 lin. in diam., cup-shaped, with 4 glands and 5 transversely rectangular or subquadrate fringed lobes, glabrous; glands 1/3– 1/2 lin. in their greater diam., transversely oblong, entire. Capsule erect, 2 lin. in diam., glabrous; styles variable, 1/3– 3/4 lin. long, free to the base, bifid at the apex. Seeds about 1 1/4 lin. long, ellipsoid, nearly smooth, but with a very faint indication of reticulation, dark brown, with a shortly stalked peltate circular caruncle.