- Name also: Chickweed, Alpine Chickweed
- Family: Pink Family – Caryophyllaceae
- Growing form: Perennial herb. Loosely tufted–forming mat-like stands.
- Height: 5–20 cm (2–8 in.). Stem limp–ascending, hairy–glabrous.
- Flower: Corolla regular (actinomorphic), white, approx. 1–2 cm (0.4–0.8 in.) wide, petals five, 9–15 mm (0.35–0.6 in.) long, approx. 1.5–2 times as long as sepals, shallowly 2-lobed. Sepals 5, tapered–blunt, often hairy, with narrow membranous margins; calyx base slightly angular. Stamens usually 10. Gynoecium syncarpous, with 5 styles. Inflorescence a 2-branched cyme, flowers 1–4(–7); subtending bracts’ membranous margin at least 0.2 mm (0.08 in.) wide.
- Leaves: Opposite, stalkless. Blade (widely) elliptic–lanceolate–almost linear, with entire margin, glabrous–straight-haired–wool-haired, often also glandular-haired, usually quite thin, sometimes slightly fleshy.
- Fruit: Cylindrical, tapering towards tip, curved, 7–16 mm (0.28–0.65 in.) long capsule splitting into 10 lobes.
- Habitat: Rocks, precipices, Lappish rock faces, gravels, fell slopes, moors, meadows, river banks, sandbanks, shores, roadsides. Ssp. lanatum is calciphile.
- Flowering time: June–August.
Alpine mouse-ear that grows on serpentine cliffs in Kaavi is endangered and other serpentine variations in central Lapland are near threatened.
Alpine mouse-ear is a very diverse plant which has three subspecies in Finland: ssp. alpinum, ssp. lanatum and ssp. glabratum. They differ from each other mainly in the amount of hair they have and their distribution. The species that are most different from each other, ssp. lanatum and ssp. glabratum, have at times been regarded as independent species. Most often subspecies appear on their own, but intermediate forms are quite common and in mixed stands the line between the different subspecies has to be drawn quite arbitrarily.
The identification markers for ssp. alpinum are straight-haired stems, leaves and sepals. It grows mainly in the fell tundra belt in dryish meadows, shrubby heaths and steep Lappish banks, but it has also spread to the fell birch and coniferous forest belt, where it occasionally grows on rock walls. It is easy to cultivate and is sometimes found in garden rockeries. Its stem and leaves are densely packed with long, white hairs, which is a typical adaptation of plants that thrive in dry, sunny spots. It grows quite rarely in northern Lapland and Kuusamo on rocky ledges and scree beds, while a separate stand is known to exist on the southern side of the Baltic, near Tallinn in Estonia. Ssp. glabratum is almost hairless, and it rarely grows with other subspecies – presumably their ecological preferences are clearly different. It favours a chalky or magnesium-rich bedrock and grows mainly in the lower alpine tundra belt. It can also be found far from the fells, at least as far south as central Finland. Outwith its main habitat in the north the plants are almost without exception small-leaved and delicate, growing only on highly alkaline magnesium silicate (a.k.a. serpentine).