Annual. Stems erect, 20–80 cm, often branched. Herbage glabrous to sparsely puberulent. Leaves distinctly petiolate; blades 1–8 cm long, divided into 3 lanceolate, serrate leaflets. Inflorescence: heads several; peduncles 1–8 cm long. Involucre: outer phyllaries ca. 8, linear-oblanceolate, 1–2 cm long, ciliate; inner phyllaries ovate, 4–8 mm long with erose, appendaged tips. Rays absent or 3 to 5, reduced. Disk corollas 2–3 mm long. Pappus 2, awns 2–4 mm long. Achenes flattened, 6–12 mm long (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
In Montana
Bidens species have opposite leaves, involucral bracts of 2 types, awned seeds that catch your clothing, and grow in wetland habitats. Several species lack ray florets.
Devil's Beggarticks -
Bidens frondosa*Life Span: Annual.
*Leaves: Pinnately divided and with a distinct petiole.
*Flower Heads: Composed of disc florets; ray florets absent or inconspicuous. Outer phyllaries are 5-8 mm long.
*Pappus: With 2 awns.
*Habitat: Wet or moist places that may become temporarily inundated.
Tall Bur-marigold -
Bidens vulgata*Life Span: Annual.
*Leaves: Pinnately divided and with a distinct petiole.
*Flower Heads: Composed only of disc florets; ray florets absent. Outer phyllaries are 10-16 mm long.
*Pappus: With 2 awns.
*Habitat: Wet or moist places that may become temporarily inundated.
Nodding Beggarticks -
Bidens cernua*Life Span: Annual.
*Leaves: Simple or shallowly lobed and toothed. Petioles are short and distinct or sessile and winged.
*Flower Heads: Composed only of disc and ray florets.
*Pappus: Usually with 4 awns.
*Habitat: Wet or moist places that may become temporarily inundated.
Three-lobe Beggarticks -
Bidens comosa*Life Span: Annual.
*Leaves: Simple or shallowly lobed and toothed. Petioles are short and distinct or sessile and winged.
*Flower Heads: Composed only of disc florets though sometimes with inconspicuous ray florets.
*Pappus: Usually with 3 awns.
*Habitat: Wet or moist places that may become temporarily inundated.
Beck Water-marigold -
Bidens beckii, SOC
*Life Span: Perennial
*Leaves: Of two types. Submerged leaves are dissected into thread-like segments. Emergent leaves are simple and toothed.
*Flower Heads: Composed only disc and ray florets.
*Pappus: Of 2-6 awns.
*Habitat: Aquatic.
POLLINATORS The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap:
Bombus griseocollis and
Bombus impatiens (Plath 1934, Colla and Dumesh 2010).
