Sessile-Leaved Tick Trefoil
Bean family (Fabaceae)
This perennial wildflower is 1½-3' tall, more or less erect, and either
unbranched or sparingly so. The central stem is light green, terete,
and hairy. Alternate trifoliate leaves occur along the entire length of
this stem; they have short petioles (nearly sessile to ¼" in length)
and leaflets that are 1-3" long and ¼-¾" across (at least 3
longer than they are across). The leaflets are narrowly oblong to
lanceolate-oblong and smooth along their margins; they are blunt at the
tips and bases. The upper surface of the leaflets is dull green and
sparsely covered with stiff appressed hairs, while the lower surface is
pale green and hairy along the veins. At the base of each trifoliate
leaf, there is a pair of small stipules that are
linear-lanceolate; these soon wither away. The central stem (and any
lateral stems) terminates in a narrow inflorescence about 6-12" long.
This inflorescence is usually a simple raceme of flowers, although
sometimes it is a sparingly branched panicle. The central stalk of
inflorescence is light to medium green and hairy. Individual flowers are about
¼" across, consisting of 5 petals that are white, pink, or rose-pink, a
short tubular calyx with 5 teeth, several stamens, and a pistil with a single style. The
petals form an upper banner and 2 wings that enclose a keel; at the
base of the banner, there is a patch of pale yellow. The hairy calyx
varies from light green to purple. Each flower has a short slender
pedicel up to ¼" long. The blooming period occurs during mid- to late summer and
lasts about 3-4 weeks. Usually, only a few flowers are in bloom at the
same time. There is no noticeable floral scent. The flowers are
replaced by flattened seedpods called 'loments' that consist of 1-3 segments with
convex upper and lower sides. The lower side of each segment is more convex that the
upper side. The loments are pale green and covered with hooked hairs.
The loments have a tendency to break apart into individual segments;
each segment contains a single seed. The root system consists of a deep
taproot. This wildflower spreads by reseeding itself.
The preference is full sun, dry conditions, and sandy soil. However,
this wildflower will tolerate partial sun and either loamy or rocky
soil. The root system adds nitrogen to the soil via symbiotic bacteria.
& Habitat: The native Sessile-Leaved Tick
Trefoil is occasional in southern, west-central, and NE Illinois, while
in the rest of the state it is rare or absent (see Distribution Map).
Habitats include dry sand prairies and typical
prairies, dry sandy savannas and typical savannas, rocky open
woodlands, limestone glades,
and roadside embankments.
Associations: The flowers are cross-pollinated primarily
long-tongued bees, which collect pollen. These floral visitors include
bumblebees, large leaf-cutting bees (Megachile spp.),
alkali bees (Nomia spp.),
and others. Some insects
feed on the foliage, flowers, or seeds of Sessile-Leaved Tick Trefoil
and other species of this genus. This includes the
several skippers, specifically: Achalarus
lyciades (Hoary Edge),
(Silver-Spotted Skipper), Thorybes
(Southern Cloudywing), and Thorybes
pylades (Northern Cloudywing).
Other insect feeders include caterpillars of the butterflies Everes
comyntas (Eastern Tailed Blue) and Strymon melinus
Hairstreak), caterpillars of the moths Hypena scabra
Cloverworm) and Grapholita
fana (Tortricid Moth sp.), leaf-mining
larvae of the Buprestid beetles Pachyschelus
confusus and Pachyschelus
laevigatus, larvae of the seed weevil Apion decoloratum, the thrips Echinothrips americanus
desmodianus, and the aphid Microparsus variabilis.
There are also several leaf beetles that feed on Tick Trefoil species,
dorsalis, and Saxinis
Some vertebrate animals also feed on
these plants. Both the Bobwhite Quail and Wild Turkey eat the seeds,
while the White-Tailed Deer, Cottontail Rabbit, horses, cattle, and
other mammalian herbivores readily consume the foliage. Because the
hooked hairs of the loments can cling to clothing and fur, the seeds
are distributed into new areas by humans and mammals.
Location: The wildflower garden of the webmaster in
Sessile-Leaved Tick Trefoil is one of the Desmodium spp. that
found in prairies. It produces smaller and fewer flowers than another
prairie species, Desmodium
canadense (Showy Tick Trefoil).
Sessile-Leaved Tick Trefoil can be distinguished from other species in
this difficult genus by its more narrow leaflets (at least 3 times as
long as across), very short petioles (¼" in length or less),
its narrow inflorescence (a simple raceme or sparingly branched