Growing form
Perennial herb. Taproot strong, erect. Runners long, branched.
Height
8–20 cm (3.2–8 in.). Stem ascending, branched at base, slightly bristly, hairy.
Flower
Corolla irregular (zygomorphic), blue–purple and base often pale, occasionally completely white, 10–14 mm (0.4–0.56 in.) long, fused at base. Petals 5; the upstanding the ‘standard’, the lateral two the ‘wings’, the lower two united to form the ‘keel’, overall shape of corolla being butterfly-like, keel often darker than other parts. Calyx 5-lobed. Stamens 10, filaments with fused bases. A single carpel. Inflorescence an axillary, long-stalked, spherical, 5–15-flowered raceme.
Leaves
Alternate, stalked, stipulate. Blade pinnate, 6–12-pairs, with terminal leaflet. Leaflets linear–elliptic, blunt, with entire margins, underside white-haired. Stipules separate.
Fruit
1–1.5 cm (0.4–0.6 in.) long, slightly curved, taper-tipped, black-haired, 2-parted, usually 6-seeded, pendent, indehiscent pod.
Habitat
Esker woods, river banks, fell heaths, rocky precipices, roadsides.
Flowering time
June–July.

Alpine milkvetch grows in the lower parts of the Lappish tundra region and in open places in the birch forest region, and this Arctic species can also be found growing on the slopes of southern Finnish ridges. When the continental ice sheet retreated from Finland at the end of the Ice Age the first plants to colonise the earth were those that could stand very cold temperatures. Gradually they made space for the steppe and finally the forest. Little pockets were left here and there, however, on rocky outcrops, slopes, banks and ridges, where fell plants and they have survived until the present day to tell their story of how plants have travelled from the south-east to the north-east as the ice sheet retreated ten thousand years ago. The area that the plant currently grows in is not constant. Its favoured habitats were earlier maintained by natural forces and animals, and nowadays the most impressive stands are often found beside roads. The species has travelled with people to new places.

Of alpine milkvetch’s subspecies, the one that grows in Finland is ssp. arcticus, which is found mainly in the north and east of the country. Ssp. alpinus is more common in Norway and Sweden. Alpine milkvetch looks very much like northern milkvetch (Oxytropis lapponica), which is rare, protected, and grows in Finland’s north-western ”arm”. Northern milkvetch’s leaflets are however grey-haired with tapered tips, and the lower part (keel) of the flower is sharp-pointed.

Astragalus alpinus

Taxonomía

Familia

Tribu

Género