Eaton's Beggarticks

Bidens eatonii may be better treated as part of B. tripartita.

Annuals, (10–)25–70(–150) cm. Leaves: petioles (narrowly, if at all, winged) 10–35+ mm; blades lance-ovate to lanceolate, (20–)35–100+ × 5–25+ mm, sometimes with 1–4 lobes near bases, bases cuneate, margins serrate, seldom ciliate, apices attenuate, faces glabrous. Heads borne singly or in 2s or 3s. Peduncles 10–35+ mm. Calyculi of (2–)3–5 ± erect, oblanceolate to linear, ± foliaceous bractlets or bracts 7–25(–70+) mm, margins sometimes obscurely ciliate, abaxial faces glabrous. Involucres usually cylindric to campanulate, rarely hemispheric, (4–)8–10(–12) × (4–)7–9 mm. Phyllaries 5–6, oblong to lance-ovate, 8–13 mm. Ray florets usually 0, sometimes 1–3+; laminae yellow-orange, 2–5(–10) mm. Disc florets 7–30+; corollas yellowish, 2.5–3.5 mm. Cypselae blackish to purplish or red-brown, ± flattened, sometimes 3–4-angled, narrowly oblanceolate, outer 5.5–10 mm, inner 6.5–11 mm, margins barbed or ciliate (proximally antrorsely, distally retrorsely), apices ± truncate, faces ± 1-nerved, glabrous or sparsely setulose, often ± striate and/or tuberculate; pappi of 2–4(–5) erect to spreading, antrorsely or retrorsely barbed awns 3–4.5 mm. 2n = 48.

Bidens eatonii var. fallax Fernald; B. eatonii var. illicita S. F. Blake; B. eatonii var. interstes (Fassett) Fassett; B. eatonii var. kennebecensis Fernald; B. eatonii var. major Fassett; B. eatonii var. mutabilis Fassett; B. eatonii var. simulans Fassett

Bidens eatonii (Eaton's beggarticks) is a North American species of flowering plant in the family Asteraceae. It is native to eastern Canada (Québec, New Brunswick, Prince Edward Island) and the northeastern United States (Maine, Massachusetts, Connecticut, New York, New Jersey).

Bidens eatonii is an annual herb up to 150 cm (60 inches) tall. It produces as many as 3 flower heads containing yellow disc florets but usually no ray florets (occasionally 1, 2, or 3). The species grows mostly along the banks of estuaries and coastal salt marshes.