Bidens vulgata Greene

Beggar Ticks

© SRTurner

Family - Asteraceae/Heliantheae

Habit - Taprooted annual forb.

Stem - Ascending to erect, to 1.5 m, glabrous or inconspicuously pubescent with sparse, cobwebby hairs, mostly at the nodes.

	Stem.
© SRTurner

Leaves - Opposite, all similar, short- to more commonly long-petiolate, the blade 3-15 cm long, broadly ovate-triangular in outline, all except rarely those of the uppermost leaves 1 time ternately or pinnately divided or compound with 3-5 segments or discrete leaflets. Leaflets lanceolate to narrowly ovate, tapered at the base, each with a well-developed stalk (this sometimes narrowly winged), tapered to a sharply pointed tip, the margins usually sharply toothed, sometimes minutely hairy, the surfaces glabrous or the undersurface sparsely to moderately pubescent with minute, fine hairs.

	Leaf.
© SRTurner

	Leaflet adaxial.
© SRTurner

	Leaflet abaxial.
© SRTurner

Heads - Inflorescences of solitary terminal heads or appearing in loose, open clusters. Heads discoid, rarely nodding at fruiting. Involucre with the outer series of 10-21 bracts 10-20 mm long, ascending to spreading, leaflike, linear to narrowly oblanceolate, the margins entire but with short, spreading hairs, at least toward the base, the outer surface glabrous or sparsely to moderately pubescent with minute, fine hairs, especially toward the base; the inner series of 8-14 bracts strongly ascending, 5-9 mm long, oblong to narrowly ovate or ovate, glabrous. Chaffy bracts narrowly oblong to oblong-lanceolate, with narrow to broad, yellowish margins but sometimes purplish-tinged at the tip.

	Inflorescence.
© SRTurner

	Heads.
© SRTurner

	Involucre.
© SRTurner

	Numerous (>9) spreading outer involucral bracts.
© SRTurner

Florets - Ray florets absent or 1-5, the corolla inconspicuous, 2-4 mm long, yellow. Disc florets 40-100(-150), the corollas 2.5-4.0 mm long, yellow. Pappus of 2 awns 3-7 mm long, these with downward-pointed barbs, erect to somewhat spreading at fruiting.

	Disks.
© SRTurner

Fruits - Achenes 5-12 mm long, wedge-shaped to oblong-obovate, awned, 1 or both faces sometimes with a fine longitudinal nerve or ridge, the angles with minute, stiff, usually ascending hairs, the faces dark brown to black, glabrous or sparsely pubescent with fine, appressed hairs.

	Receptacle and fruits.
© SRTurner

Flowering - August - October.

Habitat - Streambanks, pond margins, sloughs, ditches, moist open disturbed areas.

Origin - Native to the U.S.

Lookalikes - Bidens frondosa, also B. tripartita, B. discoidea.

Other info. - This is one of the less common species of Bidens in Missouri, though by no means rare. The flowers lack showy ray florets and are easily overlooked. It occurs in scattered locations in the state, primarily in or near floodplain regions of the large rivers. Its U.S. distribution is concentrated in the upper Midwest and New England, with some populations also found in the northwest.

This plant is easily identified to the Bidens genus by general appearance; however it strongly resembles B. frondosa and is thus easily confused with that species. The primary differentiating factor is the number of spreading leafy involucral bracts subtending the flowering heads. These are more numerous in B. vulgata (10-21) vs. B. frondosa (fewer than 9). The difference can be subtle and it is wise to examine several plants in the population.

Like most species of Bidens, this one produces barbed achenes which become a nuisance in autumn, when they tenaciously embed themselves in clothing and fur.

Photographs taken at Shaw Nature Reserve, Franklin County, MO, 8-31-2007, Frontier County Park, St. Charles County, MO, 10-7-2013, and Creve Coeur Lake Park, St. Louis County, MO, 9-17-2019 (SRTurner).