This herbaceous plant is a summer annual about 1-2½' tall that branches
occasionally to frequently. The terete to slightly angular stems are
light green, purplish green, or purple, and they are glabrous. Pairs of
opposite trifoliate leaves occur along these stems, although some of
the uppermost leaves are usually simple and alternate. The trifoliate
leaves are up to 4" long and 3" across in outline, while their petioles
are up to 1½" long. The petioles are light green to purplish green and
mostly glabrous, except for some sparse pubescence along the narrow
grooves of their upper sides. The terminal leaflets are about 1½-2"
and ½-¾" across; they are narrowly lanceolate to lanceolate in shape
and coarsely dentate along their margins. The petiolules (basal
stalklets) of terminal leaflets are about ¾" long and slender. The
lateral leaflets are about 1-1½" long and ½-¾" across; they are
lanceolate in shape and coarsely dentate along their margins. The
petiolules of lateral leaflets are very short (up to 3 mm. long). The
upper surfaces of leaflets are medium green and glabrous, while their
lower surfaces are pale green and glabrous (or nearly so). During
autumn, the leaflets often turn purple in response to cold weather.
Upper stems terminate in either individual or small clusters of 2-3
flowerheads. The peduncles of these flowerheads are relatively short
(up to 12 mm. or ½" long). Each flowerhead is about 3-6 mm. across
(excluding the outer bracts), consisting of 10-20 disk florets and no
ray florets. The corollas of disk florets are
yellow, short-tubular in shape, and 5-lobed; they are about 3 mm.
long. Originating from the base of each flowerhead, there are 2-5 leafy
outer bracts. The outer bracts are medium green, narrowly oblanceolate
or elliptic in shape, and glabrous (or nearly so); they are up to 1½"
(4 cm.) long and 8 mm. across (usually about one-half the maximum size,
but highly variable). Around the base of each flowerhead, there are
several inner bracts. These inner bracts are 4-6 mm. long, light green
or yellowish green, oblong-ovate in shape, and appressed together in a
slightly overlapping single series. The blooming occurs from late
summer into the fall, lasting about 1½-2 months. In the absence of
cross-pollination, the disk florets are self-fertile. Afterwards, the
disk florets are replaced by achenes with pairs of awns. The achenes
(excluding their awns) are about 4 mm. long, 1-1.5 mm. across, and
flattened-oblanceoloid in shape; they are truncate at their apices,
while their outer sides have faint midribs. The barbed awns of these
achenes (2 awns per achene) are about 1 mm. in length. Mature achenes
are greenish brown to dark brown.
The root system is shallow and
fibrous. This plant reproduces primarily by reseeding itself. The lower
nodes of its stems can develop rootlets when they contact moist ground.
Occasionally, colonies of plants of variable size will develop at
The preference is full or partial
sun, wet to moist conditions, and soil containing loam or decaying
organic material. Sometimes this plant establishes itself on fallen
logs or the lower trunks of trees. Standing water is tolerated if it is
The native Swamp Beggar's Ticks
is occasional in southern and central Illinois, while
in the northern section of the state it is rare or absent (see
swamps, banks of lakes, margins of ponds, low areas along rivers,
and limestone sinkholes. This plant can be found in either disturbed or
higher quality wetlands, favoring humid areas where there is some
protection from the wind.
flowerheads attract relatively few insect pollinators, although
sometimes bees (including Halictid bees) and flies (including Syrphid,
Tachinid, and bee flies) will either collect or feed on the nectar and
pollen. In general, the foliage, stems, and other parts of Bidens spp.
are a source of food for such insects as aphids (including Aphis
), larvae of the fruit fly
larvae of the leaf-mining flies Chromatomyia
, caterpillars of the butterfly
(Dainty Sulfur), larvae of several moths (including
and Epiblema otiosana
and leaf beetles
). See the Insect Table
listing of these species. The achenes or
seedheads of Bidens spp.
are consumed by some species of waterfowl,
upland gamebirds, and songbirds, including the Mallard, Wood Duck,
Greater Prairie Chicken, Ring-Necked Pheasant, Bobwhite Quail, Purple
Finch, Common Redpoll, and Swamp Sparrow (Martin et al., 1951/1961;
Havera, 1999; Schwartz, 1945). In addition, the Snapping Turtle
Blanding's Turtle (Emys
), and the
Painted Turtle (Chrysemys
) sometimes feed on the seeds and
possibly the foliage of these plants (Lagler, 1943; Ernst et al.,
The foliage is browsed sparingly by White-Tailed Deer and the
Cottontail Rabbit. The awned achenes can cling to the feathers of
birds, the fur of mammals, and the clothing of humans, which spreads
Swamp Beggar's Ticks and other Bidens
to new locations.
Border of a lake at Walnut Point State Park in
This is one of the Bidens
in Illinois with non-showy flowerheads
because it lacks ray florets. Species in this group are often referred
to as "Beggar's Ticks." Once the flowerheads are produced, Swamp
Beggar's Ticks (Bidens
) is fairly easy to distinguish from
two similar species with 2-awned achenes, namely Common Beggar's Ticks (Bidens frondosa
and Tall Beggar's Ticks (Bidens
noticeably, the flowerheads of Swamp Beggar's Ticks have fewer outer
bracts (typically 3-4) than those of Common Beggar's Ticks (typically
6-11) and Tall Beggar's Ticks (typically 13-20). In addition to having
fewer outer bracts than these species, it also has smaller achenes
with shorter awns. In contrast to the preceding species, other
non-showy Bidens spp.
in Illinois, such as Purple-Stemmed Tickseed (Bidens connata
Three-Lobed Beggar's Ticks (Bidens
), can be distinguished from the preceding species
by their 3- or
4-awned achenes. Sometimes Nodding Bur-Marigold (Bidens cernua
lacks ray florets, but it has only simple leaves and its achenes are
4-awned. In comparison to the preceding Bidens spp.
Ticks has a rather delicate appearance because of its thin leaves and
relatively small size.