Coreopsis aristosa Michaux, Fl. Bor.-Amer. 2: 140. 1803; Bidens aristosa var. fritcheyi Fernald; B. aristosa var. mutica (A. Gray) Gattinger ex Fernald

Annuals, (15–)30–60(–150) cm. Leaves: petioles 10–30 mm; blades lanceolate to lance-linear overall, 30–80(–150) × 10–30(–50) mm, usually laciniately pinnatisect, primary lobes 3–7+, 15–60+ × 2–20 mm, bases cuneate, ultimate margins laciniate to serrate, ciliate, apices acuminate, faces glabrous or sparsely scabrellous. Heads in ± corymbiform arrays. Peduncles (10–)30–80+ mm. Calyculi of 8–12(–16) usually spreading to reflexed, linear, seldom foliaceous bractlets (4–)5–7(–12) mm, margins entire, ciliate, abaxial faces glabrous or ± scabrellous. Involucres ± hemispheric or broader, 6–8(–12) × 10–15 mm. Phyllaries 7–8(–13), lance-ovate to lance-linear, 6–8(–12) mm. Ray florets (5–)8–10+; laminae yellow, 10–25 mm. Disc florets (12–)20–40+; corollas yellowish, 2–3+ mm. Cypselae red-brown to blackish, ± flattened (unequally 3–4-angled), broadly cuneate, outer (4–)5–6 mm, inner 5–7 mm (lengths mostly 1.5–2.5 times widths), margins (± corky-winged) patently to antrorsely barbed, apices truncate to concave, faces weakly striate, sometimes tuberculate, glabrous or sparsely strigillose; pappi 0, or of 2(–4) spreading to divergent, antrorsely or retrorsely barbed awns (0.5–)2–4(–6) mm.

Flowering Aug–Oct(–Nov). Marshes, meadows, pine forests, disturbed sites; 0–300 m; Ont.; Ala., Ark., D.C., Ill., Ind., Ky., La., Md., Mich., Minn., Mo., N.C., S.C., Tenn., Tex., Va.