Annuals, (10-)20-60(-180) cm. Leaves: petioles 10-40(-60) mm; blades deltate to lance-ovate overall, 30-80(-150+) × 20-60(-100+) mm, 3(-5)-foliolate, leaflets petiolulate, lanceolate to lance-ovate, (15-)35-60(-120) × (5-)10-20(-30) mm, bases cuneate, margins dentate to serrate, sometimes ciliate, apices acuminate to attenuate, faces glabrous or hirtellous. Heads usually borne singly, sometimes in 2s or 3s or in open, corymbiform arrays. Peduncles 10-40(-80+) mm. Calyculi of (5-)8(-10) ascending to spreading, spatulate or oblanceolate to linear, sometimes ± foliaceous bractlets or bracts 5-20(-60) mm, margins usually ciliate, abaxial faces glabrous or hirtellous. Involucres campanulate to hemispheric or broader, 6-9 × 7-12 mm. Phyllaries 6-12, oblong or ovate to lance-ovate, 5-9 mm. Ray florets 0 or 1-3+; laminae golden yellow, 2-3.5 mm. Disc florets 20-60(-120+); corollas ± orange, 2.5-3+ mm. Cypselae blackish to brown or stramineous, ± obcompressed, obovate to cuneate, outer 5-7 mm, inner 7-10 mm, margins antrorsely or retrorsely barbed, apices ± truncate to concave, faces usually 1-nerved, sometimes tuberculate, glabrous or sparsely hirtellous; pappi of 2 ± erect to spreading, antrorsely or retrorsely barbed awns 2-5 mm. 2n = 24, 48, 72. Flowering (Jun-)Aug-Sep(-Oct). Moist woods, meadows, thickets, fields, roadsides, railroads, borders of streams, ponds, sloughs, swamps, ditches; 10-2000 m; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Sask.; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico; introduced, Europe. Infusions and tinctures of Bidens frondosa are rated as outstanding herbal therapies for irritation, inflammation, pain, and bleeding of the urinary tract mucosa and are used for benign prostatic hypertrophy and increasing excretion of uric acid, decreasing the risk of gout attacks, as well as other medical uses (M. Moore 1993).
From Flora of Indiana (1940) by Charles C. Deam
Frequent to common or abundant throughout the state in moist places in stubble and fallow fields, woodland, and ditches and along roadsides.
Indiana Coefficient of Conservatism: C = 1
Wetland Indicator Status: FACW
FNA 2006, Wiggins 1964, Kearney and Peebles 1969, Welsh et al 1987
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Annual herb, 20-120 cm tall; stems erect, glabrous, square in cross section. Leaves: Opposite, on petioles 1-4 cm long; blades pinnately compound with 3-5 leaflets, these 2-8 cm long, lanceolate with serrate margins, the terminal leaflets on short petiolules. Flowers: Flower heads orange, usually discoid, erect on peduncles 2-10 cm long, solitary or occasionally in open panicles of 2 or 3 heads; calyculi (extra set of bracts just below the involucre) of 5-8 linear bractlets, 1-5 cm long, with ciliate margins; involucre (ring of bracts wrapped around the flower head) hemispheric, 1 cm wide, the bracts (phyllaries) 6-12, ovate, 5-7 mm long; ray flowers usually lacking but 1-3+ possible, when present the corolla laminae (ray petals) golden, 2-4 mm long; disc florets 20-60, the corollas orange, 3 mm high. Fruits: Achenes blackish, narrowly wedge-shaped, 6-10 mm, glabrous to stiffly hairy, usually with 2 barbed awns, 3-4 mm. Ecology: Found in damp, disturbed soils below 6,000 ft (1829 m); flowers August-October. Distribution: s CAN; throughout the US; south to MEX; introduced in Europe. Notes: Bidens is a genus of herbaceous plants with opposite leaves, discoid or radiate flower heads with yellow-orange flowers, and seeds (achenes) with 2-4 barbed awns. B. frondosa is a widespread annual, distinguished by its orange, usually discoid flower heads surrounded by a ring of long narrow green bracts (calyculi) which are quite a bit longer than the flower head; the ray florets, which when present are inconspicuous with ray petals only 2-3 mm long; the compound leaves with petioled leaflets; and the flattened, wedge-shaped achenes, each with 2 antrorsely barbed awns (antrorse means that the barbs point upwards). Ethnobotany: Unknown for this species, other species in this genus have many uses. Etymology: Bidens is derived from the Latin bis, twice and dens, tooth, hence meaning 2-toothed, and frondosa which means leafy. Synonyms: Bidens frondosa var. anomala, Bidens frondosa var. caudata, Bidens. frondosa var. pallida, Bidens frondosa var. stenodonta Editor: SBuckley 2010, AHazelton 2015
Annual, generally glabrous or nearly so, 2-12 dm; lvs on petioles 1-6 cm, pinnately compound, with 3-5 lanceolate, acuminate, serrate lfls to 10 נ3 cm, sometimes sparsely short-hairy beneath, at least the terminal one slender-petiolulate; heads campanulate to hemispheric, or narrower in depauperate plants, discoid or nearly so, the disk to 1 cm wide in fl; outer invol bracts 5-10, typically 8, green and ±leafy, usually conspicuously surpassing the orange disk, evidently ciliate on the margins, at least toward the base; anthers exserted; achenes flat, narrowly cuneate, strongly 1-nerved on each face, commonly dark brown or blackish, subglabrous or appressed-hairy, 5-10 mm; pappus of 2 retrorsely (seldom antrorsely) barbed awns; 2n=24, 36, 48, 72. Waste places, especially in wet soil; Nf. and N.S. to Wash., s. to Ga., La., and Calif. June-Oct.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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