Naked-Flowered Tick Trefoil
Bean family (Fabaceae)
This perennial wildflower consists of a short leafy stem (4-12" tall)
and a flowering stalk (1½-3' long) that are separated from
other at the base. The leafy stem is erect, light green to reddish green, and
short-pubescent; it has 1-2 pseudo-whorls of 3 compound leaves at its
apex. The compound leaves are trifoliate with slender petioles about
2-3" long. Individual leaflets are 2-3½" long and 1½-2½" across; they
are lanceolate-ovate to oval in shape and their margins are smooth. The
upper surface of the leaflets is medium green and short-pubescent to
glabrous, while their lower surface is pale green and glabrous. The
terminal leaflet of each trifoliate leaf has a slender petiolule (basal
stalklet) up to ¾" long, while the lateral leaflets have slender
petiolules less than 1/8" long. The erect to ascending
is light green to reddish green and short-pubescent; it is usually
leafless, although a less common variety of Naked-Flowered Tick Trefoil
has 1-2 trifoliate leaves. The upper part of the flowering stalk
consists of a raceme or narrow panicle of flowers up to 1' long. The flowers
arranged along the stalk in widely spaced pseudo-whorls. The pedicels
of the flowers and lateral branches (if any) are about ½-¾" long..
Individual flowers consist of 5 whitish pink or
pale lavender petals, a short tubular calyx with blunt teeth that is
greenish red to white, several stamens with white filaments, and a
pistil with a single style. The corolla of each flower has a typical
pea-like structure consisting of an erect banner, a straight horizontal
keel, and a pair of spreading wings. The calyx is
short-pubescent and its bottom tooth is larger in size than the others.
The blooming period occurs from mid- to late summer for about 1-1½
months. On each plant, only a few flowers are in bloom at the same time
and they are not noticeably fragrant. The flowers are replaced by
flattened seedpods called 'loments.' The loments usually have 2-3
one-seeded segments (less often, 1 or 4 segments); the upper side of
each segment is straight or slightly concave, while the lower side is
convex or rhombic. The lateral sides of each loment are covered with
short hooked hairs; each loment has a long stipe (about ½" long) at its
base and a shorter beak (less than ¼" long) at its tip. Each segment of
the loment is about 8 mm. long (a little less than 1/3"). The root
system consists of a short broad taproot or caudex. This wildflower
reproduces by reseeding itself.
The preference is
light to medium shade, mesic conditions, and a slightly to moderately acidic soil
containing sand, rocky material, or loam with decaying organic matter.
The root system of this wildflower fixes nitrogen into the soil via
& Habitat: Naked-Flowered Tick Trefoil is
occasional in central
southern Illinois, while in the northern section of the state it is
uncommon (see Distribution
Map). Habitats consist of mesic beech-maple
woodlands, sandy oak woodlands, and rocky woodlands where
sandstone is present. This wildflower occurs in higher quality
woodlands where the native ground flora is intact.
Associations: The flowers are cross-pollinated by
long-tongued bees, and Halictid bees; these visitors collect
pollen. Nectar is not available as a floral reward. Other insects feed
on the foliage and other parts of Desmodium
spp. (Tick Trefoils). These
species include the caterpillars of several skippers, butterflies, and
moths; the leaf-mining larvae of the Buprestid beetles Pachyschelus
confusus and Pachyschelus
laevigatus; the larvae of the seed weevil
Apion decoloratum; the
desmodianus; and the aphid Microparsus variabilis.
There are also several leaf beetles that feed on the foliage of tick
and Saxinis omogera.
Some vertebrate animals also use these plants as a
food source. The seeds are eaten by the Wild Turkey and Bobwhite, while
the foliage is palatable to deer, rabbits, horses, cattle, and other
mammalian herbivores. Because of the height of the flowering stalk (up
to 3') and the habitat (woodlands), White-Tailed Deer are probably the
primary transporters of the seeds of Naked-Flowered Tick Trefoil as the
loments (seedpods) can cling to fur.
Location: A sandy woodland at the Indiana Dunes National
Naked-Flowered Tick Trefoil is usually easy to identify because, unlike
other Desmodium spp.
(Tick Trefoils), it produces its leaves and
flowers on separate stalks (except for an uncommon variety). While
other species in this genus produce leaves that are clearly alternate,
Naked-Flowered Tick Trefoil produces its leaves in pseudo-whorls. This
species also has loments (a type of seedpod) with straight or slightly
concave upper sides above their segments. In contrast, most species of
tick trefoil have loments with convex upper sides above their segments.
Naked-Flowered Tick Trefoil also
prefers shady woodlands,
while other species of tick trefoil usually prefer partially
shaded savannas or sunny prairies.