Bidens tripartita L.

Erect, glabrous or almost glabrous annual, 10–80 cm tall. Stems angled, branched above to form infl. Lvs petiolate, usually simple and not lobed, sometimes deeply 1-pinnatisect with 3–5 segments, 3–10–(20) cm long; lamina or segments narrowly ovate-elliptic to lanceolate, coarsely and often unevenly serrate, acuminate. Upper cauline lvs becoming smaller, shortly petiolate or apetiolate, not lobed and less distinctly serrate. Capitula 4–10 mm diam. Outer involucral bracts 3–4, foliaceous, glabrous, linear, 6–12 mm long; inner bracts many, membranous, ovate-elliptic to ovate-triangular, 5–8 mm long, with dark lined centre and pale margins. Receptacular scales similar to inner bracts but narrower. Florets all ☿, tubular, yellow-orange. Achenes flattened, ovate-cuneate to obtriangular, with 1 slender to prominent rib on each face, dark brown, ciliate and otherwise glabrous to sparsely hairy, 5–8 mm long; awns 2–4, often unequal, 0.5–2.7 mm long.

[From: Webb et al. (1988) Flora of New Zealand. Volume 4.]

Flowering: Feb.–Mar.