Description: This adventive biennial plant consists of a rosette of basal leaves during the first year, bolting upward during the second year to produce flowers and seeds. Mature second-year plants are about 2-3½' tall. The basal leaves are usually double pinnate with long petioles. In outline, they are up to 10" and 4" across (including the petioles), narrowing gradually toward their tips. Each compound leaf is subdivided into leaflets that are usually pinnate, while the secondary leaflets are entire, cleft, or coarsely toothed. The individual leaflets are rather narrow, providing the compound leaves with a lacy or fern-like appearance. Scattered white hairs often occur along the petioles, or along the margins and lower mid-veins of the leaflets. The round stems of bolting plants are finely ribbed and have scattered white hairs; they are hollow on the inside and branch sparingly. The compound leaves along the stems are alternate and have their petioles enclosed by sheaths. Otherwise, they are similar to the basal leaves in appearance.
The flowering stalks are long and largely
devoid of leaves, terminating in compound umbels of small white flowers. Each
compound umbel has a whorl of green bracts at its base that are pinnatifid with
linear segments. The flat-topped compound umbel is about 2-5" across and
consists of about 30 umbellets. Each umbellet has a whorl of linear green
bracts at its base and consists of about 30 flowers. While the flowers are
blooming, their slender pedicels are often white or greenish white. Each flower
consists of 5 white petals and 5 stamens, spanning about 1/8" across. However,
the central flower of the central umbellet is often reddish purple. There are
forms of Wild Carrot where all of the flowers are light pink, light purple, or
reddish purple; the latter color is particularly rare. The blooming period
occurs from mid-summer to early fall and lasts about 2 months. There is no
noticeable floral scent, although the foliage has a slightly bitter carrot-like
scent because of the presence of saponins and possibly other chemicals. Each
flower produces a single ribbed seed that is ovate in shape. It is flat on one
side, but rounded on the other, with white bristly hairs along the ribs. The
color of the seeds is variable, depending on their maturity. They are initially
light reddish purple, turning green and then greyish brown. As the seeds
mature, the compound umbels start to close and assume a shape that is more or
less spheroid. They can become detached from the flowering stalks and blow
about in the wind. The root system consists of a stout taproot that is white
and runs deep into the ground. This plant spreads by reseeding
itself.
Cultivation: This species
usually grows in locations with full sunlight, mesic to dry conditions, and a
clay-loam soil that is not too acidic. However, it will also adapt to moist
conditions and other kinds of soil. Wild Carrot is aggressive and can be
difficult to destroy. It often survives mowing and hand-pulling of
plants by
the rootstocks. This is because the deep taproot is difficult to remove and
stores considerable energy to initiate new growth.
Range & Habitat: Wild Carrot is a very common
plant that occurs in every county of Illinois (see
Distribution
Map). It is adventive from Europe and has existed in the United States for
quite some time. Habitats include thickets, degraded prairies or meadows, areas
along railroads and roadsides, lawns, pastures, abandoned fields, fence rows,
vacant lots, junk yards, and other waste areas. Fire is not very effective in
removing this plant from natural habitats, where it can be moderately invasive.
Faunal Associations: The nectar of
the flowers attracts many kinds of insects, especially flies and wasps,
including parasitoid Gasteruption spp. (Wild Carrot Wasps). The foliage
is eaten by the caterpillars of the butterfly Papilio polyxenes asterias
(Black Swallowtail). The seeds cling to the feathers of birds and fur of
mammals and are distributed by them. It has been shown that the seeds can pass
through the digestive tracts of livestock and remain viable, which provides
another method of distribution. The foliage is not a preferred source of food
to mammalian herbivores; nonetheless, it is eaten occasionally by rabbits and
cattle. With the exception of the Ring-Necked Pheasant, most birds don't use
the seeds as a food source. Blue Jays have been known to use the foliage of
Wild Carrot in the construction of their nests. This practice appears to be
beneficial, as it reduces the number of nest lice and other parasites,
producing healthier hatchlings with a higher survival rate. Apparently, the
foliage of Wild Carrot contains an insecticide or insect
repellant.
Photographic Location: A
weedy meadow at Judge Webber Park in Urbana, Illinois.
Comments: Wild Carrot is an ubiquitous plant that
most people can recognize. It is possible, however, to confuse this introduced
species with other white-flowered members of the Carrot family. Wild Carrot
doesn't begin blooming until mid-summer and usually occurs in mesic to dry
areas, rather than wetlands. The presence of a single reddish purple flower in
the middle of the compound umbel is a distinctive characteristic, although it
is not always present. There is a similar native species, Daucus
pusillus (Small Wild Carrot), that occurs in two counties of southern
Illinois. The primary bracts of the compound flowers for this species are
double pinnate, whereas the primary bracts of the introduced species are single
pinnate. Wild Carrot is an important source of the natural food dye, carotene,
and for this reason has commercial importance. According to most authorities,
it is the source of the cultivated carrot.