Glomerate Mouse-Eared Chickweed
Cerastium glomeratum
Pink family (Caryophyllaceae)

Description: This adventive plant is a winter or spring annual about 4-10" tall. It has a small tuft of erect to ascending leafy stems; these stems are light green to dark purple, terete, and hairy. Along each stem, there are pairs of sessile opposite leaves at intervals. Individual leaves are up to ¾" long and about half as much across; they are medium green, bluntly ovate, broadly oblong, or obovate with smooth margins. Both the lower and upper surfaces of each leaf are covered with hairs. The hairs on the stems and leaves may have a sticky texture from minute glandular secretions.

Each stem terminates in a dense cluster of flowers; in addition, individual or small clusters of flowers may develop from the axils of the upper leaves. Each small flower is about ¼" across, consisting of 5 white petals, 5 green sepals, 10 stamens, and a pistil with 5 styles. The tips of the petals are notched. The lanceolate sepals have long forward-pointing hairs and membranous margins. The hairy pedicel of each flower is no longer than 5 mm. (1/5") in length, even when it has transformed into a seed capsule. The blooming period occurs from mid-spring to early summer and lasts about 3-4 weeks. Each flower transforms into a cylindrical seed capsule that is up to twice the length of the persistent sepals. This seed capsule is membranous along the sides and open at the apex, where there are 10 tiny teeth. At the bottom of this capsule, there are several tiny seeds. Each seed is obovoid or heart-shaped, somewhat flattened, and minutely pebbly on the outer surface. The root system is shallow and fibrous. This plant spreads by reseeding itself; it often forms colonies in favorable habitats.

Cultivation: This little weed prefers partial to full sun and moist to slightly dry conditions. It is often found in soil containing loam, clay-loam, or other material. This species can invade lawns to some extent.

Range & Habitat: Glomerate Mouse-Eared Chickweed is occasional throughout Illinois (see Distribution Map). Habitats include openings in rocky woodlands, grassy meadows, lawns, pastures, fallow fields, roadsides, and waste ground. Areas with a history of disturbance are preferred. This species is native to Eurasia.

Faunal Associations: The nectar and pollen of the flowers attract small bees (Halictid & others) and flies (Syrphid & others). The caterpillars of the moths Agrostis venerabilis (Venerable Dart), Haematopis grataria (Chickweed Geometer), and Lobocleta ossularia (Drab Brown Wave) feed on chickweeds. Among vertebrate animals, the Mourning Dove and various sparrows occasionally eat the seeds, while the foliage is eaten by the Cottontail Rabbit and Woodchuck.

Photographic Location: A lawn at a state park in west-central Indiana.

Comments: The distinctive characteristic of this chickweed is its dense cluster(s) of flowers. In particular, the pedicels of the flowers are the same length or shorter than the sepals (5 mm. or less). Several other species of chickweeds are similar in appearance, but at least some of their pedicels exceed 5 mm. in length (particularly when their flowers have transformed into seed capsules). The sepals of Glomerate Mouse-Eared Chickweed are somewhat unusual because they are covered with long forward-pointing hairs that may extend beyond their margins; other species of chickweed have sepals with shorter hairs. In general, the various species in the Cerastium genus are called "Mouse-Eared Chickweeds" because of the shape and hairiness of their leaves; these species usually have 10 stamens and 5 styles per flower. A scientific synonym of Glomerate Mouse-Eared Chickweed is Cerastium viscosum. Because of this defunct scientific name, this species is sometimes called "Clammy Mouse-Eared Chickweed."

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