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Little Mouse-ear

Cerastium semidecandrum

  • Name also: Fivestamen Chickweed
  • Family: Pink Family – Caryophyllaceae
  • Growing form: Annual herb.
  • Height: 5–12 cm (2–5 in.). Stem ascending–erect, hairy, with glandular hairs, at least in crown, flowerless basal shoots not present.
  • Flower: Corolla regular (actinomorphic), white, approx. 1 cm (0.4 in.) wide; petals five, 2–4 mm (0.08-0.15 in.) long, shorter (or occasionally longer) than sepals, shallowly 2-lobed, sometimes of varying form and size. Sepals 5, lanceolate, tapered, hairy, glabrous at tip, with broadly membranous margins. Stamens usually 5–10, most usually 5. Gynoecium syncarpous, usually with 5 styles. Inflorescence 2-branched cyme, flowers 10–40; subtending bracts with broadly membranous margins.
  • Leaves: Opposite, stalkless. Blade elliptic, hairy, with entire margin, greyish green.
  • Fruit: Cylindrical, straight–slightly curved, 5–7 mm (0.2-0.3 in.) long capsule splitting into (9–)10 lobes.
  • Habitat: Rocks, sun-baked meadows, sandy slopes, railwaysides, roadsides, wasteland.
  • Flowering time: May–June.

Little mouse-ear is the type of plant that loves dry, open, sandy habitats. It flowers in spring and the beginning of summer, making use of the moistness of spring. Mouse-ear flowers are mainly visited by flies and bees, and annual species often ensure fertilization through self-pollination. Little mouse-ear ripens its seeds, withers and dies by high summer. The seeds are not troubled by the level of salt in the Baltic Sea and seed sprouts can even float undamaged for at least a month. Little mouse-ear probably spread to Finland on the currents: it is relatively rare on the southern coast compared to the south-west archipelago, where it is most common. The species also grows casually further north, and further inland too. Little mouse-ear is an essential part of the natural vegetative cover on hills and rocks, but it has exploited human activity by taking over new habitats too, on sports fields and roadsides.

Differentiating little mouse-ear from sticky mouse-ear chickweed (C. glutinosum) can be difficult because both are often sticky-haired. The differences are however clear if one knows what to look for: little mouse-ear’s flower-stalks are descending oblique at the end of its flowering time and the subtending bracts and sepals have wide membranous margins; sticky mouse-ear chickweed’s flower-stalks are on the other hand erect or ascending oblique, and the subtending bracts and sepals have only narrow membranous margins. Little mouse-ear differs from common mouse-ear (C. fontanum) in that it has no flowerless shoots. Differentiating small, glandular-haired common mouse-ear, which have no basal shoots, from little mouse-ear could require the aid of a loupe: the tip of little mouse-ear’s glandular hairs is round, while common mouse-ear’s are always elongated.

Other species from the same genus
Other species from the same family

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