Astragalus polaris is a minute, trailing member of the pea family (Fabaceae) found in moist alpine areas in tundra and gravelly sites, often associated with limestone bedrock. The loosely tufted plants arise from a central rhizome. Leaves are pinnate, with 7-17 tiny elliptic to obovate leaflets, often cuneate at the tips, up to 5 mm long. The racemes are 1-3 flowered, the flowers pale purple. The calyx is covered in black or white hairs. The pods become inflated and papery in maturity, a distinguishing characteristic for this species.
Astragalus polaris is perennial and flowers in early to mid-summer.
Members of the genus Astragalus are insect pollinated, especially by bees. The fruit is a pod, which splits open at maturity to release its seeds to be dispersed by gravity and water.
Astragalus polaris is a amphi-Beringian endemic species, occurring in Alaska, the Yukon, and rarely in the Russian Far East. In Alaska, A. polaris occurs in the Alaska Range, the Brooks Range, and along the western coast, from the Alaska Peninsula to Point Hope. In Denali, this species occurs along the northern side of the Alaska Range, as well as in the alpine zone near Mystic and Shellabarger Pass, and in the alpine in the upper Chulitna River drainage.
Astragalus polaris is an alpine species, most commonly occurring above 1100 meters. It is found equally frequent on all aspects, but plants on southern aspects tend to occur at high elevations. North-facing populations are found on a wider variety of slopes, however. Astragalus polaris is found on a wide variety of angles, but it prefers slopes above 28 degrees.