Bidens vulgata
Pittonia 4: 72. 1899.
Annuals, (15–) 30–50 (–150) cm. Leaves: petioles 10–50 mm; blades ± deltate to ovate overall, 50–100 (–150+) × (15–) 30–80 (–120+) mm, usually laciniately 1-pinnatisect or 3–5-foliolate, primary lobes or leaflets ± lanceolate, 20–80 (–120) × 10–25 (–40+) mm, blades rarely 2–3-pinnatisect, bases cuneate, ultimate margins dentate to serrate, little, if at all, ciliate, apices acute to attenuate, faces glabrous or ± hispidulous. Heads borne singly or in 2s or 3s or in open, corymbiform arrays, erect. Peduncles (10–) 40–150+ mm. Calyculi of 10–16 (–21) ascending to spreading, spatulate to linear, seldom foliaceous bractlets or bracts 10–20 (–40) mm, margins usually hispid-ciliate, abaxial faces ± hispidulous. Involucres hemispheric or broader, 5–6 × 8–10 mm. Phyllaries 10–12, ovate to lanceolate, 6–9 mm. Ray-florets 0 or 3–5+; laminae pale-yellow, 2.5–3.5 mm. Disc-florets 40–60 (–150+); corollas yellow, 2.5–3.5 mm. Cypselae purplish, brown, olive, or stramineous, ± flattened, obovate to cuneate, outer 6–10 mm, inner 8–12 mm, margins (sometime ± winged) proximally antrorsely, distally retrorsely barbed, apices ± truncate, faces obscurely 1-nerved, sometimes tuberculate, glabrous or sparsely strigillose; pappi of 2 erect to divergent, retrorsely barbed awns 3–4 (–7) mm. 2n = 24, 48.
Phenology: Flowering Aug–Sep(–Oct).
Habitat: Ditches, shores of lakes and streams, swamps, marshes, moist woods, roadsides, railroads, fields, waste areas
Elevation: 10–1000 m
Distribution
Alta., B.C., Man., N.B., N.S., Ont., Que., Sask., Ark., Calif., Colo., Conn., Del., D.C., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Vt., Va., Wash., W.Va., Wis., Wyo., in Europe
Discussion
Bidens vulgata is similar to B. frondosa; it is more robust. Both are phenotypically plastic. Locally, B. vulgata often matures earlier than B. frondosa.
Selected References
None.