Description: This native annual plant is 1-3' tall, branching occasionally in the upper half. The stems are glabrous or have a few scattered white hairs; they are often red in bright sunlight, otherwise green. The compound leaves are oddly pinnate, consisting of 3-5 leaflets. Sometimes, there are a few simple leaves near the flowerheads. These leaves occur alternately or oppositely along the stems. The compound leaves have long petioles. The leaflets are up to 3" long and 1" across. They are lanceolate, coarsely serrated, and usually hairless, although their lower surface may be slightly pubescent. Their tips are rather long and pointed.
Some of the upper stems terminate in a
single flowerhead about ¾–1" across on a long stalk; there may be 1
or 2 smaller flowerheads lower on the stalk. The flowerheads consist of
numerous disk florets that are golden yellow; the ray florets are absent or
barely perceptible. There are 5-10 leaf-like outer bracts surrounding the
flowerheads; usually they are 8 in number. These bracts are green, and slightly
ciliate or hairy, especially near the base of the flowerhead. The blooming
period is usually late summer or early fall, and lasts about a month. There is
no noticeable floral scent. The achenes are nearly black and rather slender,
but becoming slightly wider toward the awns. These awns are long and slender,
with tiny barbs that point downward. The root system consists of a shallow
taproot that branches frequently. During the fall, the leaves often turn dark
red.
Cultivation: The preference is
partial or full sun, and moist conditions; light shade is also tolerated. The
soil should be fertile, with sufficient organic material to retain moisture.
Occasional flooding and poor drainage is tolerated, if not preferred. This
plant is easy to grow, and can become a weedy pest. Sometimes it is found in
more mesic situations, but the plants will be smaller in size and less
robust.
Range & Habitat: Common
Beggar-Ticks occurs in most counties of Illinois, and is quite common; official
records probably underestimate its occurrence in some areas (see
Distribution
Map). Habitats include moist areas of black soil prairies; moist meadows
near woodlands or rivers; floodplain woodlands and young flatwoods; thickets;
marshes, swamps, seeps, and borders of ponds or
lakes; low-lying areas along railroads and roadsides; both cultivated and
abandoned fields; drainage ditches and miscellaneous waste areas. This plant
likes disturbed areas.
Faunal
Associations: The nectar of the flowers attract fewer insects
than Bidens spp. with showier flowers. Occasionally, they are visited by
bumblebees, Halictid bees, wasps, bee flies, Tachinid flies, small butterflies,
and other insects. The caterpillars of several species of moths feed on the
foliage or pith of the stems, including Epiblema otiosana (Bidens Borer
Moth), Platysenta mobilis (Mobile Groundling), Condica
confederata (The Confederate), Cirrophanus triangulifer (Goldenrod
Stowaway), and Palthis asopialis (Faint-Spotted Palthis). The seeds are
eaten by small rodents and various birds, including the Ring-Necked Pheasant,
Bobwhite, Swamp Sparrow, and Purple Finch. The Cottontail Rabbit occasionally
eats the foliage. The awns of the seeds readily cling to the fur of animals and
clothing of humans, thus promoting the spread of this plant far and
wide.
Photographic Location: The
above photographs were taken near a drainage ditch in Judge Webber Park,
Urbana, Illinois.
Comments: This is
one of the more common Bidens spp. The species in this genus can be
divided into two groups: those with showy flowers, and those with non-showy
flowers. Common Beggar-Ticks is a member of this latter group. The non-showy
Bidens spp. in Illinois can be distinguished from each other by
considering two characteristics: 1) whether most of the leaves are simple or
pinnately compound, and 2) the number of outer bracts surrounding the
flowerheads. Common Beggar-Ticks has pinnately compound leaves and 8 outer
bracts (usually) surrounding the flowerheads. It is quite similar in appearance
to Bidens vulgata (Tall Beggar-Ticks), except that this latter plant
usually has 13 outer bracts surrounding the flowerheads.