Bidens polycephala Sch. Bip.

Erect subshrubs 0.5–2 m tall. Leaves simple or very rarely (Nuku Hiva) compound and trifoliolate, 3–15.5 cm long including petiole, blades lanceolate to elliptic-lanceolate, 2–11 × 1.2–5 cm, glabrous or lower surface occasionally pubescent, especially on young leaves, margins variably serrate to serrulate or subentire, apex acuminate or occasionally acute or caudate (Nuku Hiva). Heads 10–80(–100+), glabrous to sparsely pubescent at base, in diffuse cymes terminating main stem and lateral branches, main inflorescence axis up to 6.5 cm, heads 2–5 mm in diameter excluding rays, peduncles 0.1–5 cm long, glabrous or sparsely pubescent; outer involucral bracts 1–4.5 mm long, well differentiated from inner bracts, glabrous to sparsely ciliate; ray florets 3–12 per head, sterile, rays yellow, 3–12 × 1–4 mm, apex rounded, entire or bi- or tri-lobed; disk florets ca. 12–25, perfect. Achenes gray to black, straight or slightly curved, 3–8 × 0.5–1 mm, margin setose; pappus of 0–2 short awns. n = 36 (Gillett 1972).

Marquesas Islands, occurring on Nuku Hiva, Ua Huka, Hiva Oa, Mohotani, and Tahuata, 10–800(–1080) m. The occurrence on Mohotani is based on observation by Jean-François Butaud (pers. comm., 2014), but should be verified by collections.