- Family: Butterwort Family – Lentibulariaceae
- Growing form: Perennial herb. Roots long, thick, juicy.
- Height: 10–20 cm (4–8 in.). Stem leafless, almost hairless scape, usually 1–4.
- Flower: Corolla irregular (zygomorphic), white, 10–16 mm (0.4–0.64 in.) long, fused, bilabiate, spurred. Upper lip 2-lobed, lower lip 3-lobed with yellow spots, spur short, broad, arching, blunt, yellowish, 2–3 mm (0.08–0.12 in.) long. Calyx bilabiate, 5-lobed. Stamens 2. Gynoecium composed of 2 fused carpels. Flowers solitary, terminating scapes.
- Leaves: In basal rosette. Blade elliptic, 2–5 cm (0.8–2 in.) long, pale lime green–reddish brown, edges curling upwards. Sticky leaf surface with glandular hairs and secreting glands.
- Fruit: Capsule open at tip.
- Habitat: Fens, seepage surfaces, stream banks, damp rock walls.. Calciphilous.
- Flowering time: June–July.
It is very difficult – if not impossible – to tell alpine butterwort and common butterwort (P. vulgaris) apart when they are not in bloom, so botanists often mix the species up with each other. The flower, on the other hand, has good, clear identification markers in the colour of the corolla, the form of the spur and the hairiness of the inflorescence. These differences do not go unnoticed by pollinators: alpine butterwort is mainly pollinated by flower flies, but also anthomyiid flies and house flies, while common butterwort attracts mainly honeybees and bumblebees. As the species bloom only partly at the same time and have different pollinators, wild hybrids have never been found. The butterworts have a specialised pollination system: as the insect inserts its proboscis into the nectar store it cannot avoid touching the broad recurved stigma lobe, which the pollen that the visiting insect has brought from another flower sticks to. Contact makes the stigma turn in the opposite direction, enclosing the pollen within.
According to its scientific name, alpine butterwort is primarily a fell plant, which in Finland grows mainly in Lapland. It favours calciferous soil and appears in suitably nutritious areas on the south-western Enontekiö fells, as well as fens and springs in Kuusamo, Salla, Tervola and Pudasjärvi. Although alpine butterwort’s roots are better developed than its relatives’, it supplements its diet by trapping small insects and spiders. Butterworts assimilate with their chlorophyll cells and their carnivorous diet supplies nitrogen, which is otherwise sparse in their habitats. Its trapping leaves are in a rosette, tight against the ground, where small insects roaming over the ground stumble easily into the trap and get caught on the sticky surface. The leaves press themselves so firmly against the soil that when the plant is picked its leaves can be seen to have curved round tight against the roots. The significance of this is not known. Despite their special and enigmatic qualities, it is best to leave butterworts to grow in peace.