Pink family (Caryophyllaceae)
Description: This adventive annual plant produces stems about ½1' 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 ½1" in length and ¼½" 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. Each leave is more or less ovate, smooth along the 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 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" long (about 3-5 mm.). The slender pedicels are finely pubescent. The blooming period occurs during the spring for plants that are winter annuals, and during the summer or fall for plants that are summer annuals. A typical plant will bloom sporadically for 1-2 months. Each flower is replaced by a seed capsule that is light brown with 6 small teeth along its upper rim; it contains several seeds. Each mature seed is dark reddish brown, somewhat flattened, and nearly orbicular; its surface has tiny pebbles. 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 is quite common. It is native to Eurasia. Habitats include woodland areas prone to flooding, thickets, cropland and fallow fields, lawns and gardens, nursery plots, areas adjacent to buildings, and miscellaneous waste areas. While this species occurs to a limited extent in natural habitats, it prefers areas with a history of disturbance.
Faunal Associations: The nectar and pollen of the flowers attract Andrenid bees, Halictid bees, and various kinds of flies, including Syrphid flies, Muscid flies, Flesh flies, and Anthomyiid flies. In the absence of such visitors, the flowers can self-pollinate. The caterpillars of some moths feed on the foliage, including Agrotis venerabilis (Venerable Dart), Haematopis grataria (Chickweed Geometer), Lobocleta ossularia (Drab Brown Wave). Small granivorous songbirds eat the seeds (see Bird Table), while Chickens and possibly some upland gamebirds eat both the foliage and seeds. Among mammalian herbivores, the Cottontail Rabbit and hogs eat the foliage without apparent ill-effect.
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. The Chickweeds 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 has only 3 styles. It differs from the others in this genus by the large size of its sepals (at least 1/8" long), which are conspicuously longer than the petals of the flowers. The foliage of Common Chickweed resembles Stellaria pallida (Apetalous Chickweed) to a remarkable degree; however, the flowers of Apetalous Chickweed lack petals and their 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.