A prostrate evergreen plant 2 or 3 in. high, whose woody stems are covered with the persisting bases of fallen leaves and brown bark, which ultimately peels off. Leaves oval, oblong or ovate, usually heart-shaped at the base, blunt at the apex, with mostly four to eight large teeth or lobes along each margin, 1⁄3 to 11⁄4 in. long, 1⁄4 to 1⁄2 in. wide, dark dull green with hairs along the midrib above, white with down beneath; stalk 1⁄4 to 1⁄2 in. long, very slender, downy. Flowers solitary on an erect downy stalk 1 to 3 in. high, lengthening at the fruiting stage; they are 1 to 13⁄4 in. wide, white; petals usually eight, oval-oblong, rounded at the end; sepals eight, linear, 3⁄8 in. long, covered with pale wool outside. The fruit is somewhat like that of a clematis, each of the numerous seed-vessels being terminated by a tail 1 in. or more long, furnished over its whole length with silky hairs.
Native of the high latitudes and altitudes of the northern hemisphere; widely spread over the mountainous parts of the British Isles. Among other places I have seen it freely scattered over the rocky hills in the neighbourhood of Arncliffe in Yorkshire, flowering there in July and August. It is of easy cultivation but appears to prefer limestone rock and is excellently adapted for the rock garden.
f. argentea (Blytt) Hulten D. 0. var. argentea Blytt; D. 0. var. vestita Beck – Leaves silver-hairy on the upper surface as well as below. Found in Norway and in the Eastern Alps (Lower Engadine, Tyrol and Upper Styria), more rarely further west. This form belongs to the typical subspecies (subsp. octopetala), which is the only race of the mountain avens found in W. Europe.
D. integrifolia Vahl D. 0. var. integrifolia (Vahl) Hook. f. – Leaves to 1⁄2 in. or a little more long, 1⁄4 in. or less wide, narrow-lanceolate to oblong, entire or more rarely with a few teeth near the base. Native of Greenland, northern N. America and the Kolyma Peninsula.
More distinct is:
D. drummondii Hook. – This has the same habit and the leaves are similarly white beneath and lobed at the margin, but they are tapered at the base and longer stalked; the flowers differ in being pale yellow instead of white; the flower-stalk is usually taller (sometimes 9 in.) and more conspicuously downy. Filaments of anthers hairy (glabrous in D. octopetala). Native of the high latitudes of N. America; first discovered by Richardson, the botanist, who accompanied Sir John Franklin on his first voyage to the Polar Sea, 1819-22. It must soon after have been introduced as it was figured in the Botanical Magazine in 1830 (t. 2972).
D. × suendermannii Kellerer ex Suenderm. – A hybrid between the above and D. octopetala. Flowers (in the type) yellow in bud, afterwards white. Described from a cultivated plant, but such crosses occur in the wild where the two species are in contact.