Description: This
native plant is a winter annual (less often, a spring annual) about 1' tall. It
consists of a rosette of basal leaves about 6" across, from which one or
flowering stalks develop. The basal leaves are bipinnatifid; they have long
slender petioles. Each leaflet is broadest at the middle or toward its tip,
tapering to a short blunt point; it is often cleft with two lateral lobes that
are smaller than the middle lobe. The foliage of Large-Bracted Corydalis (both
leaves and stalks) is greyish green and glabrous. The stalks are sprawling or
ascending, reaching up to 1½' in length. Occasionally, a flowering stalk
will branch and develop lateral flowering stalks. Each stalk terminates in a
spike-like raceme of flowers with leafy bracts. Each flower has a tubular
yellow corolla about ¾" long, consisting of 2 outer petals and 2 inner
petals. The upper outer petal forms a short upper lip in front that curls
upward and a rather long spur in back. The lower outer petal forms a long lower
lip that functions as a landing pad for visiting insects. There is a patch of
white toward the throat of the corolla. Underneath each flower is a single
leafy bract about ½" long. This bract is either ovate or divided into
lobes with short blunt tips. A typical raceme will have several flower buds at
its apex, about 4-8 flowers in bloom near the middle, and developing seedpods
below. Each seedpod is slightly flattened and about 1" long, terminating in a
slender beak at its tip; it contains about 6-12 seeds. Relative to the
spike-like raceme, the seedpods are more or less ascending and often curve
upward slightly. The blooming period for plants that are winter annuals occurs
during late spring, while plants that are spring annuals bloom during
mid-summer. A typical plant will remain in bloom for about a month. The root
system consists of a taproot. This plant spreads by reseeding
itself.
Cultivation: The preference
is full or partial sun, mesic to dry conditions, and sandy soil. This plant
also grows readily in gravelly or loamy soil; if it is grown in moist loamy
soil, taller and more aggressive plant species should be kept away from it.
Foliar disease and insects are not normally troublesome. The seeds will
germinate after a short dormancy period; they can be planted during the fall or
early spring.
Range & Habitat:
Large-Bracted Corydalis is an uncommon plant that occurs in a few counties in
western Illinois. Prior to 1986, it was incorrectly identified as another
species of Corydalis. Recently, several large populations of Large-Bracted
Corydalis have been discovered, therefore it is more common in Illinois than
previously believed. However, it is still state-listed as "threatened." This
species is more common in the south-central states; western Illinois lies at
the northeast corner of its range. Habitats include sand prairies, sandy fallow
fields, and sandy or gravelly areas along roads and railroads (including the
ballast). Disturbed areas are preferred, particularly where ant hills occur.
Occasional wildfires, sand blow-outs, and overgrazing by herbivores are
probably beneficial in maintaining the populations of this
plant.
Faunal Associations: The
flowers are pollinated by bumblebees. The oily appendages of the seeds
(elaisomes) attract ants (particularly Pheidole bicarinata), which
undoubtedly help to disperse the seeds. The poisonous foliage is avoided by
mammalian herbivores.
Photographic
Location: The wildflower garden of the webmaster in Urbana,
Illinois.
Comments: Both the flowers
and foliage are quite attractive. Large-Bracted Corydalis can be distinguished
from other Corydalis spp. by its long yellow flowers (exceeding 2/3" in
length) and their large leafy bracts (exceeding 1/3" in length). Other
Corydalis spp. in Illinois have shorter bracts and/or shorter flowers.
There are other varieties of Corydalis curvisiliqua, but they occur in states
that lie southwest of Illinois.