This biennial wildflower forms a low rosette of leaves during its first
year, followed by a flowering stem (1-3' tall) with alternate leaves
during the following year. The basal leaves are 2½-5" long and ½-1¼"
across; they are usually oblanceolate or shallowly pinnatifid in shape
and sparsely dentate along their margins. The upper and lower surfaces
of the basal leaves are nearly glabrous to moderately pubescent. The
central stem is grayish green, terete, and unbranched; it is
usually sparsely hairy below and glabrous above.
alternate along the entire length of this stem, becoming slightly
smaller as they ascend. These leaves are 2-4" long and ½-1¼" across;
they are oblanceolate, elliptic, or lanceolate in shape, smooth or
slightly undulate along their margins, and sparsely dentate, tapering
gradually to sessile bases. The upper surface of the leaves is medium
green and glabrous (or nearly so), while the lower surface is
light-medium green and sparsely pubescent. The central stem terminates
in a raceme of flowers about 4-16" long. The flowers bloom near the
apex of the raceme, while seedpods develop below. Each flower is about
¼" long and a little less across, consisting of 4 white petals, 4 green
sepals, 6 stamens, and a pistil with a short style. The petals
only a little longer than the sepals. The sepals are bluntly lanceolate
and pubescent. The pedicels of the flowers are slender and slightly
pubescent; as the seedpods develop, they become ¼-½" in length and
droop downward. The seedpods
(siliques) are 1½-4" long,
cylindrical, flattened, and glabrous; they droop downward and
become somewhat curved. Each seedpod contains many seeds that are
arranged in a single row; the seedpod eventually divides into 2 parts
along its length to release them. Each seed is about 2-3 mm.
long, 1.5-2.5 mm. across, and somewhat flattened; the body of
seed is surrounded by a broad membrane. The seeds are blown about by
the wind. The root system consists of a taproot.
Sicklepod prefers partial sun to light shade and mesic to dry
conditions. It adapts to many types of soil, including those that are
rocky or sandy. During dry periods, the lower leaves tend to wither
The native Sicklepod is occasional
throughout Illinois. Habitats consist of rocky
upland woodlands, sandy savannas, wooded slopes, partially
cliffs, thinly wooded bluffs, thinly wooded sand dunes, and areas along
woodland paths. Sicklepod is usually found in hilly areas that are
partially shaded, whether rocky or sandy. Occasional wildfires are
beneficial in maintaining populations of this species.
The nectar and pollen of the flowers attract
primarily small bees and flies. These insects cross-pollinate the
flowers. Other insects feed destructively on the foliage, flower buds,
and other parts of Sicklepod and other Arabis spp
Cresses). These species include the flea beetles Phyllotreta conjuncta
, and the caterpillars of the following Pierid
(Falcate Orangetip), Euchloe olympia
(Olympia Marble), Pieris
(Mustard White), and Pontia protodice
(Checkered White). Very little appears to be known about Sicklepod's
interrelationships with vertebrate animals.
Along a path on a wooded sand dune at the
Indiana Dunes State Park in NW Indiana.
Like most species of its genus, Sicklepod lacks showy flowers, although
its long arching seedpods are distinctive and eye-catching. It is one of several
native Arabis spp.
(Rock Cresses) that can be found in Illinois.
Sicklepod can be distinguished from similar species by its sessile
leaves and drooping seedpods. Other species of this genus within the
state have leaves that clasp the stem or their seedpods are more erect.
As a result of recent genetic analysis, some authors have assigned
Sicklepod to a different genus; they refer to it as Boechera canadensis