11.
Bidens vulgata
Greene, Pittonia. 4: 72. 1899.
Bident vulgaire
Bidens frondosa
Linnaeus var.
puberula
Wiegand;
B. puberula
(Wiegand) Rydberg;
B. vulgata
var.
dissectior
Sherff;
B. vulgata
var.
puberula
(Wiegand) Greene;
B. vulgata
var.
schizantha
Lunell
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.
2
n
= 24, 48.
Flowering Aug—Sep(—Oct). Ditches, shores of lakes and streams, swamps, marshes, moist woods, roadsides, railroads, fields, waste areas; 10—1000 m; 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.; introduced in Europe.
Bidens vulgata
is similar to
B. frondosa
; it is more robust. Both are phenotypically plastic. Locally,
B. vulgata
often matures earlier than
B. frondosa
.
