This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Rootstock prostrate, stems ascending, simple, pubescent, 3'-8' high. Stipules membranous; basal leaves slender-petioled, digitately 5-foliolate (rarely 3-foliolate); leaflets obovate, obtuse at the apex, narrowed or cuneate at the base, glabrous above, pubescent along the margins and on the veins beneath, green both sides, incisely dentate, with rounded or blunt teeth, 6"-9" long; flowers few, terminal, loosely cymose, yellow, 6"-9" broad; pedicels slender; petals obovate, obcordate, cuneate, yellow, orange-spotted at the base, longer than the ovate acutish calyx-lobes; stamens about 20; style filiform, terminal; achenes glabrous.
Potentilla Ranśnculus Lange, of Greenland and Labrador, differs in having the teeth of the leaflets lanceolate and acute.
Potentilla nivea L. Sp. Pl. 499. 1753.
Stems 2'-6' high, woody at the base, ascending or erect, silky-villous, the flowering ones mostly simple. Stipules membranous, silky; leaves 3-foliolate (very rarely 5-foliolate), the lower petioled; leaflets obo-vate, oblong or oval, obtuse, incised-dentate or cre-nate, densely white-pubescent beneath, green and loosely villous above, 4"-8" long, the terminal one generally cuneate, the others narrowed or rounded at the base; flowers 1-5, terminal, pedicelled, yellow, 5"-9" broad; bractlets lanceolate to linear; sepals silky, lanceolate, acute, shorter than the broadly obovate emarginate petals, longer than the bractlets; stamens about 20; style filiform, terminal; achenes glabrous.
Potentilla Vahliąna Lehm., another high boreal species, differs in having oval or ovate bractlets and leaflets yellowish-villous beneath.
Potentilla nana Willd.; Schlecht. Berl. Mag. 7: 296. 1815.
Stems villous-pubescent, tufted, ascending or erect, 1'-4' high. Stipules ovate or oblong, membranous, mostly obtuse, entire; leaves 3-foliolate, the basal slender-petioled; leaflets obovate, 2"-6" long, incised-dentate with acute teeth, of which the terminal one is generally the largest, generally villous on both sides, the terminal one narrowed or cuneate, the others sometimes broad at the base; flower solitary, rarely 2, yellow, 5"-7" broad; calyx-lobes ovate, obtuse, pilose, equalling the oblong bractlets, shorter than the obovate ob-cordate petals; stamens about 20; style filiform; achenes glabrous.
Labrador, Greenland and arctic America to Alaska. Also in eastern Siberia and Spitzbergen. Summer.