Pink family (Caryophyllaceae)
Description: This annual plant produces stems about ½–1' long that usually sprawl across the ground. It branches abundantly near the base, but very little toward the tips of the stems. The somewhat succulent stems are green or burgundy; they often have lines of white hairs. Pairs of opposite leaves occur at intervals along these stems. These leaves become larger toward the tips of the stems, spanning up to ¾" in length and ½" across. The leaves toward the base of the plant usually have short petioles that are slightly hairy, while the leaves near the tip of each stem are usually sessile. The leaves are oval-ovate, entire (toothless) along their margins, and hairless on the upper surface; the lower surface is occasionally hairy.
Individual flowers occur from the axils of the outer pairs of leaves, while the stems terminate in small cymes of white flowers. Each flower is about ¼" across, consisting of 5 white bifid petals (appearing to be 10 petals), 5 green sepals, 3 white styles, 2-10 stamens, and a light green ovary in the center. The sepals are lanceolate, hairy on the outer surface, and longer than the petals; each sepal is at least 1/8" (3 mm.) long. The slender pedicels are finely pubescent. The blooming period occurs during the spring for plants that are winter annuals, and during the summer or autumn for plants that are summer annuals. A typical plant will bloom sporadically for 1-2 months. Each flower is replaced by a cylindrical seed capsule that is light brown with 6 small teeth along its upper rim; it contains several seeds. Each mature seed is reddish brown, somewhat flattened, and orbicular-reniform; its surface is minutely bumpy. The root system is shallow and fibrous. This plant spreads by reseeding itself; it can also spread vegetatively by rooting at the leaf nodes along the stems.
Cultivation: Typical growing conditions consist of partial or full sun, moist to mesic conditions, and a fairly fertile loam or clay-loam soil. Light shade and temporary flooding are tolerated.
Range & Habitat: Common Chickweed occurs in every county of Illinois and it is quite common. This plant is native to Eurasia. Habitats include woodland areas prone to flooding or standing water, thickets, cropland and fallow fields, lawns and gardens, nursery plots, areas adjacent to buildings, and miscellaneous waste areas. While Common Chickweed occurs to a limited extent in natural habitats, where it is sometimes invasive, this plant prefers areas with a history of disturbance.
Faunal Associations: The nectar and pollen of the flowers attract primarily small bees and flies, including cuckoo bees (Nomada spp.), Halictid bees, Andrenid bees, Syrphid flies, bottle flies (Lucilia spp.), Muscid flies, and Tachinid flies. Less common floral visitors include nectar-seeking butterflies and parasitoid wasps. In the absence of such visitors, the flowers of Common Chickweed can self-pollinate. Some insects feed on the foliage and other parts of Common Chickweed. These species include both the adults and larvae of Cassida flaveola (Pale Tortoise Beetle) and the larvae of such moths as Agrotis venerabilis (Venerable Dart), Haematopis grataria (Chickweed Geometer), and Lobocleta ossularia (Drab Brown Wave); see Clark et al. (2004) and Covell (1984/2005). Vertebrate animals also feed on Common Chickweed and other Stellaria spp. The seeds of such plants are eaten by the Mourning Dove, Chipping Sparrow, House Sparrow, White-crowned Sparrow and Field Sparrow; the Ruffed Grouse also browses on the leaves. The Bird Table displays a more complete list of these seed-eating birds. The foliage, flowers, and seeds are a minor source for various mammals, including the Cottontail Rabbit, Groundhog, and White-tailed Deer (Martin et al, 1951/1961). The seeds are able to pass through the digestive tracts of White-tailed Deer and remain viable, spreading Common Chickweed to new areas (Myers et al, 2004). Other herbivorous mammals probably spread the seeds in their feces as well. The Prairie Deer Mouse eats the seeds of Common Chickweed to a minor extent (Houtcooper, 1978).
Photographic Location: A field in Savoy, Illinois.
Comments: This is probably the best known chickweed in Illinois, although it can be confused with other species. Chickweed species fall into 2 large groups: those with 3 styles (Stellaria spp.) and those with 5 styles (Cerastium spp.). Like other Stellaria spp. (Chickweeds), Common Chickweed (Stellaria media) has only 3 styles. It differs from the others in this genus by length of its sepals (at least 1/8" long), which are conspicuously longer than the petals of its flowers, and by the relatively broad shape of its leaves. The foliage of Common Chickweed resembles Apetalous Chickweed (Stellaria pallida) to a remarkable degree – however, the flowers of Apetalous Chickweed lack petals and its sepals are shorter. The blooming period of Apetalous Chickweed is restricted to the spring, while Common Chickweed often blooms later in the year. Common Chickweed is somewhat variable in the hairiness of its leaves, the length of its stems, and the number of stamens in each flower.