- Name also: Arctic Pearlwort
- Family: Pink Family – Caryophyllaceae
- Growing form: Perennial, loosely tufted herb.
- Height: 3–10 cm (1.2–4 in.). Stem limp–ascending, glabrous, rooting.
- Flower: Corolla regular (actinomorphic), white, sometimes reddish, approx. 5 mm (0.2 in.) diameter; petals five, 2 mm (0.08 in.) long, sepals 5, same length as petals, widely ovate, blunt. Stamens 10 (sometimes 5). Gynoecium syncarpous, with 5 styles. Flowers solitary. Flower and capsule stalks straight (nodding in bud phase). Buds spherical.
- Leaves: Opposite, stalkless, united in pairs. Blade linear, thread-like, with entire margin, glabrous, dark green, short-tipped.
- Fruit: Elongated egg-shaped, 3.5 mm (0.14 in.) long capsule splitting into 5 lobes, clearly longer than calyx.
- Habitat: Snow-bed sites on fell tundra, melt-water wetlands, Lappish rock faces, rocky banks, meadows and also roadsides.
- Flowering time: July–August.
As well as beautiful campions and impressive carnations, the Pink family includes small, insignificant-looking and often difficult to identify species. They have adapted to grow where larger flowers cannot, and all they need is a small patch of bare ground. There are plenty of places in the extreme environment of the fells that larger competitors are unable to colonise. Being small is therefore an advantage: close to the ground, out of reach of the cold wind, it is relatively warm. In winter a thin covering of snow is enough to insulate the plant against the biting cold.
Alpine pearlwort’s Finnish habitat is centred around north-western Lapland, where sharp-eyed wanderers can find it among sparse vegetation – snow-bed sites, solifluctions, Lappish rock faces and stream banks. The most abundant stands are around the Enontekiö fells, where it grows on riverbanks in the birch-forest belt as well as in tundra. Its close relative snow pearlwort (S. nivalis) also thrives in snow-bed sites, solifluctions, Lappish rock faces and stream banks. Alpine pearlwort’s calyx and corolla are 5-leaved, while snow pearlwort is both 4 and 5-leaved.
Apart from pearlworts, Pink family members that grow in tundra and that also benefit from their small size are the stitchworts, of which 3 species grow in Finland: mountain sandwort (Minuartia biflora) mountain stitchwort (M. rubella) and teesdale sandwort (bog stitchwort, M. stricta). Arctic sandwort (Arenaria norvegica) and fringed sandwort (A. pseudofrigida) are also small tundra plants but they have relatively big flowers and wider leaves than pearlworts and stitchworts. Arctic sandwort is only known to grow on the Saana and Malla fells in Lapland, while tundra sandwort grows in the ravines of Kuusamo and Salla.