Bidens aristosa (Michx.) Britt.

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.

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

Bidens aristosa seeds

Bidens aristosa is a North American species of plants in the sunflower family. Common names include bearded beggarticks, western tickseed, long-bracted beggarticks, tickseed beggarticks, swamp marigold, and Yankee lice. It is native to eastern and central United States and south-central Canada, from Maine south to Florida and west as far as Ontario, Texas, and Nebraska. It grows in wet meadows and abandoned fields.

Bidens aristosa is an annual herb occasionally reaching 150 cm (5 feet) in height. It has numerous yellow flower heads with both ray florets and disc florets. Fruits are dry achenes bearing barbs that get caught in fur or clothing, thus aiding in the plant's dispersal. The plant attracts native bees.

Bidens aristosa là một loài thực vật có hoa trong họ Cúc. Loài này được (Michx.) Britton mô tả khoa học đầu tiên năm 1893.