Bidens hyperborea

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.

Flowering Aug-Oct. Marshes, borders of estuaries; 0-10 m; N.B., N.S., Nunavut, Ont., Que.; Maine, Mass., N.H., N.Y.

Annual 1-7 dm, glabrous or the stem scabrous-hispid; lvs oblanceolate to narrowly lance-elliptic or narrowly oblong, not ciliate, sessile except sometimes the lower, acute to more often acuminate, 2-10 cm נ3-10 mm, with a few small teeth or subentire; heads erect or occasionally nodding, discoid or with rays to nearly 1 cm, narrow, campanulate or turbinate, the disk 5-15 mm wide; outer invol bracts 4-8, leafy, ascending-erect, lance-linear, 1.5-4 cm; disk-corollas (3)4(5)-lobed; anthers included; achenes narrowly cuneate, flat or nearly so, blackish, coarsely striate, 4-7 mm, the summit finally cartilaginous and somewhat convex; pappus of 2-4 retrorsely barbed awns; 2n=24, 36. Estuaries; Mass. (and reputedly N.Y.) to N.S. and Que.; James Bay. Aug., Sept.

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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