Bidens laevis (L.) Britt., Stern & Poggenb.

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.

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 are 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, red-brown, 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.

Helianthus laevis Linnaeus, Sp. Pl. 2: 906. 1753; Bidens chrysanthemoides Michaux; B. helianthoides Kunth; B. nashii Small; B. quadriaristata de Candolle

Bidens laevis is a species of flowering plant in the daisy family known by the common names larger bur-marigold and smooth beggarticks. It is native to South America, Mexico, and the southern and eastern United States. It grows in wetlands, including estuaries and riverbanks.

Bidens laevis is similar in appearance to its relative Bidens cernua and the two are sometimes confused. This is an annual or perennial herb growing over 20 centimeters tall and sometimes much taller, exceeding one meter in height and sometimes approaching two. The narrow lance-shaped leaves are 5 to 15 centimeters long, with finely toothed edges and pointed tips. The inflorescence bears one or more flower heads which bend down as they become heavy with fruit after flowering. Each head has a center of yellow disc florets and a fringe of 7 or 8 yellow ray florets each up to 3 centimeters long. The fruit is a dry achene with sharp barbs that adhere to fur and clothing, thus helping the plant with seed dispersal.