Common Mouse Ear Chickweed

Cerastium fontanum is a highly variable and complex species. It often has been reported as C. vulgatum Linnaeus, an ambiguous name; see discussion under the genus.

Plants perennial (rarely annual), tufted to mat-forming, often rhizomatous. Stems: flowering stems erect from decumbent base, branched proximally, 10-45 cm, softly pubescent, eglandular with straight hairs; nonflowering shoots, when present, produced proximally, decumbent, rooting at nodes, branched, 5-20 cm, often subglabrous with alternating lines of eglandular hairs; small axillary tufts of leaves usually absent. Leaves not marcescent; blade 10-25(-40) × 3-8(-12) mm, densely covered with patent to ascending, colorless, long, eglandular hairs; leaves of flowering shoots in distant pairs, sessile, blade elliptic to ovate-oblong, apex subacute; leaves of sterile shoots pseudopetiolate, often spatulate, blade oblanceolate, apex obtuse. Inflorescences lax, 3-50-flowered cymes; bracts lanceolate, reduced, herbaceous, eglandular-pubescent, distal often with narrow, scarious margins. Pedicels somewhat curved distally, 2-10(-20) mm, longer than sepals, densely pubescent with patent, eglandular, rarely glandular hairs. Flowers: sepals ovate-lanceolate, 5-7 mm, margins narrow, apex acute, scarious, pubescent with eglandular, rarely glandular, hairs; petals oblanceolate, 1-1.5 times as long as sepals, apex deeply 2-fid; stamens 10, occasionally 5; styles 5. Capsules narrowly cylindric, curved, 9-17 mm, ca. 2 times sepals; teeth 10, erect, margins convolute. Seeds reddish brown, 0.4-1.2 mm, bluntly tuberculate; testa not inflated, tightly enclosing seed. 2n = 122-152, usually 144.

Herbs short-lived perennial or annual, 15--40 cm tall. Stems caespitose or simple, suberect; sterile stems decumbent; flowering stems pilose and/or glandular pubescent all round. Basal leaves ovate, obovate-lanceolate, ovate-spatulate, or spatulate, 5--13 × 3--10 mm, both surfaces pilose, base attenuate into a petiole; cauline leaves subsessile, ovate, oblong, or narrowly ovate-oblong, 1--3(--4) × 0.3--1(--1.2) cm, both surfaces pilose or pubescent, margin densely ciliate, apex acute. Cyme terminal, spreading, lax, up to 40-flowered; bracts leaflike, ovate, 3--5 mm, both surfaces glandular pubescent. Pedicel slender, 0.5--2.5 cm, densely glandular pubescent, recurved after anthesis. Sepals oblong- or ovate-lanceolate, 5--6 mm, abaxially densely glandular pubescent, margin membranous or narrowly so. Petals obovate or obovate-oblong, shorter than to 2 × as long as sepals, apex 2-lobed. Stamens shorter than petals. Ovary ovoid, ca. 2 mm. Styles 5, linear, slightly longer than ovary. Capsule cylindric, 8--10 mm, ca. 2 × as long as calyx, 10-toothed, teeth usually recurved. Seeds brown, usually 0.4--0.8 mm in diam., tuberculate. Fl. Apr--Jun, fr. May--Jul.

Anhui, Fujian, Gansu, Guangdong, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [cosmopolitan weed].

Forests, forest margins, mountain slopes, hilltop grasslands, fields, sandy soils, rock crevices, roadsides; 100--4300 m.