About Astragalus alpinus L.
Astragalus alpinus L. is a variable perennial herb that grows from a taproot and rhizome network, topped by an underground caudex. Its roots host nitrogen-fixing nodules. Aboveground stems reach up to 30 centimetres (12 in) long, and are mostly decumbent, growing to form a mat. Its leaves grow up to 15 centimetres long, and are divided into several pairs of leaflets that each reach up to 2 centimetres (5⁄6 in) long. The inflorescence is a raceme that holds up to 30 flowers, each around 1 centimetre (1⁄3 in) long, and colored purple or blue. The fruit is a legume pod up to 1.7 centimetres (2⁄3 in) long that contains seeds. This species is widespread across Eurasia. In North America, it ranges from Alaska to Newfoundland, and extends south as far as Nevada and New Mexico. It grows in subalpine and alpine climates, most often in moist habitats including woodlands and meadows surrounding streams and lakes. It also grows on tundra and other cold, dry, exposed sites, including gravel bars and scree. It sometimes acts as a pioneer species, colonizing land during the primary stage of ecological succession, such as roads and bare ground turned over by frost heave. It has been observed regrowing early in recently burned areas in Grand Teton National Park, and can also grow in already vegetated areas. Individual plants growing in harsh conditions are smaller than individuals growing in more favorable sites. This species provides food for caribou, Arctic hares, greater snow geese, small blue butterflies, and grizzly bears. The species may be split into two varieties: var. alpinus, which occurs in the Arctic, and var. brunetianus, which occurs at lower latitudes in northeastern North America.
