Estuary Beggarticks

Annuals, (5–)10–30(–70+) cm. Leaves sessile or petioles 5–25 mm (± winged); blades oblanceolate to linear, 15–40(–100+) × (3–)6–10(–15+) mm, bases cuneate, margins entire or ± serrate, sometimes ciliate, apices rounded or obtuse to attenuate, faces glabrous. Heads borne singly or in 2s or 3s. Peduncles 10–60 mm. Calyculi of 2–3(–9) erect, oblanceolate to lance-linear (± foliaceous) bractlets or bracts (6–)10–20(–75+) mm, margins usually ciliolate, abaxial faces glabrous. Involucres usually ± campanulate to cylindric, sometimes ± hemispheric, 5–7(–9) × (4–)7–10 mm. Phyllaries 6–8(–12), oblong, 6–11 mm (tips usually yellow, as are tips of paleae). Ray florets 0 or 3–7; laminae pale yellow, 4–12 mm. Disc florets 15–30(–60); corollas yellow (often orange-tipped), 3–4 mm. Cypselae blackish to olive, flattened, narrowly cuneate, outer 4–9 mm, inner 5–10 mm, margins retrorsely barbed, apices ± truncate to convex, faces ± 1-nerved, ± striate, glabrous; pappi of (2–)3–4 ± erect, retrorsely barbed awns 2–5 mm.

Bidens hyperborea var. arcuans Fernald; B. hyperborea var. cathancensis Fernald; B. hyperborea var. colpophila (Fernald & H. St. John) Fernald; B. hyperborea var. gaspensis Fernald; B. hyperborea var. svensonii Fassett

Bidens hyperborea (common names estuary beggarticks, northern beggar-ticks or estuary bur-marigold) is a coastal species of flowering plant in the family Asteraceae. It grows along the coasts of Hudson Bay, the Arctic Ocean, and the North Atlantic Ocean in eastern Canada (Labrador, Nunavut, Ontario, Quebec, New Brunswick, Nova Scotia) and the northeastern United States (Maine, New Hampshire, Massachusetts, New York).

Bidens hyperborea is an annual herb up to 70 cm (28 inches) tall. It produces yellow flower heads sometimes one at a time, sometimes 2 or 3, each containing both disc florets and (usually) ray florets. The species grows in salt marshes and along the banks of marine estuaries.