Tickseed Sunflower (Bearded Beggarticks)

Bidens aristosa

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Photo of many tickseed sunflower flowerheads.
Tickseed sunflower, Bidens aristosa, has many common names. Eleven different species of Bidens have been recorded for Missouri.
Jim Rathert
Other Common Name
Beggar's Ticks; Bur Marigold
Family

Asteraceae (daisies, sunflowers)

Description

Tickseed sunflower is a much-branched annual or biennial. Hairless or with sparse hairs. Flowerheads daisylike, bright yellow, about 1¼ inches across, with usually 8 pointed ray florets. Bracts under flowerhead in 2 dissimilar rows; outer series spreading or reflexed, linear, not leaflike, with hairs along the margins; inner series lanceolate to narrowly ovate. Blooms August–October. Leaves opposite, pinnately (like a feather) deeply lobed or compound with 3–7 divisions, pointed, each with sharp teeth. Fruit flattened, black, with 2 needlelike awns that attach themselves to clothing and pets, thus the names “tickseed” and “beggar-ticks.”

Similar species: Eleven species of Bidens have been recorded in Missouri, plus 6 of the similar genus Coreopsis. Distinguishing among these species involves many anatomical features, including leaf characteristics, numbers of ray and disk florets, configuration of involucral bracts, and details of the fruits, right down to their barb-covered awns.

Size

Height: usually to 3 feet, occasionally to 5 feet.

tickseed_sunflower_beggar_ticks_bottomland_10-6-14.jpg

Photo of tickseed sunflowers completely filling a bottomland field.
Tickseed Sunflower (Bearded Beggar-Ticks)
Tickseed sunflower, in bloom, can create massive displays in moist bottomlands.

tickseed_sunflower_beggar_ticks_flowers_10-6-14.jpg

Photo of tickseed sunflower flowerheads.
Tickseed Sunflower (Bearded Beggar-Ticks)
The flowerheads of tickseed sunflower usually have 8 ray florets. The bracts under the flowerhead are in 2 dissimilar rows.

tickseed_sunflower_beggar_ticks_colony_10-6-14.jpg

Photo of tickseed sunflower colony in a field.
Tickseed Sunflower (Bearded Beggar-Ticks)
Tickseed sunflower grows in wet situations of prairies, waste places, ditches, roadsides, and railroads.

tickseed_sunflower_beggar_ticks_plants_10-6-14.jpg

Photo of many tickseed sunflower plants.
Tickseed Sunflower (Bearded Beggar-Ticks)
By hitchhiking on the fur of animals, the seeds of tickseed sunflower travel away from the parent plants.

tickseed_sunflower_beggar_ticks_wallpaper_10-6-14.jpg

Photo of thousands of blooming tickseed sunflower plants in a field.
Tickseed Sunflower (Bearded Beggar-Ticks)
As their common names suggest, beggar-ticks (in the genus Bidens) are closely related to the genus Coreopsis (tickseed).
Habitat and conservation

Occurs in bottomland prairies, upland prairies, bottomland forests, margins of ponds and lakes, sloughs, and fens; also crop fields, fallow fields, railroads, roadsides, and open, disturbed areas. Often grows in massive displays in moist bottomlands. Although this species is in the sunflower family, it is not in the same genus as true sunflowers (Helianthus).

image of Tickseed Sunflower Bearded Beggar Ticks Bur Marigold distribution map
Distribution in Missouri

Scattered to common statewide.

Status

As their common names suggest, beggar-ticks (in the genus Bidens) are closely related to the genus Coreopsis (tickseed). Not only can it be difficult to tell the difference among species within each genus, but also it can be tricky even to separate the two genera. DNA analysis has shown that both genera are not natural units. As scientists unlock the genetic and ancestral relationships of these plants, be prepared for some regrouping and renaming of them in the future.

Human connections

This species is sometimes grown by native wildflower and butterfly gardeners, but because it self-seeds abundantly it can become quite weedy. The seeds are an annoyance to hikers, who must pick them from pants and socks. Pets and livestock can also collect the seeds in their fur.

Ecosystem connections

Birds and mammals eat the seeds, and many insects visit the flowers. By hitchhiking on the fur of animals, the seeds travel away from the parent plants. This reduces inbreeding and helps ensure that at least some offspring may find a suitable, safe environment in which to grow.