Bidens laevis

(Linnaeus) Britton

Prelim. Cat., 29. 1888.

Basionym: Helianthus laevis Linnaeus Sp. Pl. 2: 906. 1753
Synonyms: Bidens chrysanthemoides Michaux Bidens helianthoides Kunth Bidens nashii Small Bidens quadriaristata de Candolle
Treatment appears in FNA Volume 21. Treatment on page 215. Mentioned on page 208.

Annuals (sometimes persisting), (10–) 20–60 (–120+) cm. Leaves (sometimes in 3s or 4s) sessile; blades obovate or elliptic to lanceolate or linear, (20–) 50–100 (–160+) × (5–) 10–25 (–40+) mm, bases cuneate to rounded, margins usually coarsely dentate to serrate, sometimes ciliate, apices acute to acuminate, faces glabrous. Heads (erect at flowering, sometimes nodding in fruit) borne singly or in open, ± corymbiform arrays. Peduncles (10–) 20–60 mm. Calyculi of 5–7 (–9+) erect or spreading to reflexed, oblanceolate or lanceolate to linear, often foliaceous bractlets or bracts (6–) 10–12 (–20+) mm, margins usually ciliate, abaxial faces glabrous or bases hispidulous. Involucres turbinate to hemispheric or broader, (4–) 6–8 (–10+) × 8–12+ mm. Phyllaries 8–12, ovate or obovate to lance-oblong, (4–) 6–8 (–10+) mm (tips often orange to purplish, as tips of paleae). Ray-florets usually 7–8, rarely 0; laminae orange-yellow, (10–) 15–25 (–30) mm. Disc-florets (25–) 60–100 (–150+); corollas yellow to orange-yellow, 3–6.5 mm. Cypselae blackish, redbrown, or stramineous, obcompressed, flattened or unequally 3–4-angled, ± cuneate, outer 6–8 mm, inner 8–10 mm, margins retrorsely ciliate or barbed, apices ± truncate to convex, faces ± 1-nerved, ± striate, glabrous; pappi of 2–4 ± erect, retrorsely barbed awns 3–5 mm. 2n = 22, 24.


Phenology: Flowering Aug–Oct(–Dec).
Habitat: Meadows, marshes, and margins of pools, streams, estuaries
Elevation: 0–2800 m

Distribution

V21-523-distribution-map.gif

Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Ind., Ky., La., Maine, Md., Mass., Miss., Mo., Nev., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Tex., Va., W.Va., Mexico, Central America, South America, Pacific Islands (Hawaii)

Discussion

Bidens laevis and B. cernua are similar in gross appearance; specimens of one are sometimes misidentified as the other. Perhaps they represent extremes of a single species.

Selected References

None.

Lower Taxa

None.
... more about "Bidens laevis"
not tailed +, rounded +  and obtuse +
dark +  and pale +
connate +  and distinct +
dentate to serrate +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
indeterminate +  and determinate +
John L. Strother +  and Ronald R. Weedon +
(Linnaeus) Britton +
ciliate +  and barbellate +
2 +  and 4 +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
hispidulous +
cuneate +  and rounded +
Helianthus laevis +
compound +  and simple +
10 cm100 mm <br />0.1 m <br /> (16 cm160 mm <br />0.16 m <br />) +
2.5 cm25 mm <br />0.025 m <br /> (4 cm40 mm <br />0.04 m <br />) +
5 cm50 mm <br />0.05 m <br /> (10 cm100 mm <br />0.1 m <br />) +
elliptic;lanceolate or linear +
10mm;25mm +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
1.2 cm12 mm <br />0.012 m <br /> (2 cm20 mm <br />0.02 m <br />) +
spreading +  and reflexed +
lanceolate;linear +
barbellulate +  and barbellate +
yellow +  and orange-yellow +
0.3 cm3 mm <br />0.003 m <br /> (0.65 cm6.5 mm <br />0.0065 m <br />) +
stramineous +, redbrown +  and blackish +
cuneate +, 3-4-angled +, flattened +  and obcompressed +
fertile +  and bisexual +
fertile +  and bisexual +
sessile +  and petiolate +
Ala. +, Ariz. +, Ark. +, Calif. +, Colo. +, Conn. +, Del. +, D.C. +, Fla. +, Ga. +, Ind. +, Ky. +, La. +, Maine +, Md. +, Mass. +, Miss. +, Mo. +, Nev. +, N.H. +, N.J. +, N.Mex. +, N.Y. +, N.C. +, Ohio +, Pa. +, R.I. +, S.C. +, Tenn. +, Tex. +, Va. +, W.Va. +, Mexico +, Central America +, South America +  and Pacific Islands (Hawaii) +
0–2800 m +
tuberculate +, striate +  and scabrellous +
linear-fusiform;4-angled;ovate;orbiculate;oblong;linear;cuneate +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Meadows, marshes, and margins of pools, streams, estuaries +
discoid +  and radiate +
disciform +  and discoid +
in open , more or less corymbiform arrays +  and singly +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
0.8 cm8 mm <br />0.008 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.8 cm8 mm <br />0.008 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
0.6 cm6 mm <br />0.006 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
turbinate;hemispheric +
0.8 cm8 mm <br />0.008 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
2.5 cm25 mm <br />0.025 m <br /> (3 cm30 mm <br />0.03 m <br />) +
orange-yellow +
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
whorled +  and opposite +
deltate +
barbed +  and dentate +
0.6 cm6 mm <br />0.006 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
2-carpellate +
less flat;slightly navicular +
persistent +
of 1-2 , smooth to ciliate or barbed awns or scales +  and coroniform +
1 cm10 mm <br />0.01 m <br /> (2 cm20 mm <br />0.02 m <br />) +
2 cm20 mm <br />0.02 m <br /> (6 cm60 mm <br />0.06 m <br />) +
Flowering Aug–Oct(–Dec). +
0.8 cm8 mm <br />0.008 m <br /> (1 cm10 mm <br />0.01 m <br />) +
connate +  and distinct +
8 +  and 12 +
0.6 cm6 mm <br />0.006 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
Prelim. Cat., +
styliferous +  and neuter +
bearing subulate enations +, hairy +  and bristly +
convex;flat +
exalbuminous +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Bidens chrysanthemoides +, Bidens helianthoides +, Bidens nashii +  and Bidens quadriaristata +
Bidens laevis +
species +
toothed +, serrate +, laciniate +  and dentate +
60 cm600 mm <br />0.6 m <br /> (120 cm1,200 mm <br />1.2 m <br />) +
20 cm200 mm <br />0.2 m <br /> (60 cm600 mm <br />0.6 m <br />) +
shrub +  and subshrub +