Bidens pilosa
Bidens beckii
bident poilu, cobbler's pegs, common beggar-ticks, hairy beggar-ticks, Spanish needle
Beck's beggar-ticks, Beck's water-marigold, bident de Beck, Henderson's water-marigold, Oregon water-marigold, water beggarticks, water-marigold
petioles 10–30(–70) mm;
blades either ovate to lanceolate, 30–70(–120) × 12–18(–45) mm, or 1-pinnately lobed, primary lobes 3–7, ovate to lanceolate [linear], (10–)25–80+ × (5–)10–40+ mm [blades 2(–3)-pinnatisect], bases truncate to cuneate, ultimate margins serrate or entire, usually ciliate, apices acute to attenuate, faces pilosulous to sparsely hirtellous or glabrate.
sessile; submersed blades multifid (2–3+-pinnatisect), ultimate lobes filiform, mostly 0.1–0.3 mm diam.;
aerial blades ovate to lanceolate, 10–45+ × 5–20+ mm, bases cuneate, margins pectinately incised to serrate or entire, not ciliate, apices obtuse to acuminate or attenuate, faces glabrous.
10–20(–90) mm.
(10–)20–100 mm.
turbinate to campanulate, 5–6 × (6–)7–8 mm.
± hemispheric, 7–12 × 12–15 mm.
0 or (3–)5–8+;
laminae whitish to pinkish [yellowish], 2–3 or 7–15+ mm.
8;
laminae yellow, 10–15 mm.
20–40(–80+);
corollas yellowish, (2–)3–5 mm.
10–30+;
corollas pale yellow, 5–6 mm.
(7–)8–9(–13), lanceolate to oblanceolate, 4–6 mm.
7–8+, ovate, 7–10 mm.
(6–)7–9(–13) ± appressed, spatulate to linear bractlets (3–)4–5 mm, margins ciliate, abaxial faces usually hispidulous to puberulent.
of 5–6 usually spreading, oblong to obovate bractlets 5–8 mm, margins entire, not ciliate, abaxial faces usually glabrous.
usually borne singly, sometimes in open, ± corymbiform arrays.
usually borne singly.
outer red-brown, ± flat, linear to narrowly cuneate, (3–)4–5+ mm, margins antrorsely hispidulous, apices ± truncate or somewhat attenuate, faces obscurely 2-grooved, sometimes tuberculate-hispidulous;
inner blackish, ± equally 4-angled, linear-fusiform, 7–16 mm, margins antrorsely hispidulous, apices ± attenuate, faces 2-grooved, tuberculate-hispidulous to sparsely strigillose;
pappi 0, or of 2–3(–5), erect to divergent, retrorsely barbed awns (0.5–)2–4 mm.
(outer and inner ± alike) yellowish to greenish brown, nearly terete or weakly 4-angled, ± linear, 10–15 mm, margins not barbed or ciliate, apices truncate, faces smooth or ± striate, glabrous;
pappi of 2(–6) divergent to patent, retrorsely barbed (on distal 1/4 or so) awns 13–25(–40) mm.
= 24, 36, 48, 72.
= 26.
Bidens pilosa
Bidens beckii
R. Ballard (1986) adopted a narrower circumscription of Bidens pilosa than that used here. He used: B. pilosa for plants with outer phyllaries 7–10, ray florets usually 0 (when present, laminae 2–3 mm), disc florets 35–75, pappi of 3(–5) awns 1–3 mm, and 2n = 72; B. alba for plants with outer phyllaries (8–)12(–16), ray florets 5–8 (laminae 5–16 mm), pappi of 2 awns 1–2 mm, and 2n = 48; and B. odorata for plants with outer phyllaries (6–)8(–12), ray florets 5–8 (laminae 3–18 mm), disc florets 12–61, pappi 0, or of 1–2 awns 1–3 mm, and 2n = 24.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
M. L. Roberts (1985) presented a strong case for treating Bidens beckii as Megalodonta beckii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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