in N. L. Britton et al., N. Amer. Fl. 22: 147. 1905 ,.
Plants solitary or tufted, with bulbils on branched caudices, rhizomatous. Leaves basal; petiole rounded, 3–30 cm; blade reniform to round, 2–9 cm, thin or slightly fleshy, sometimes thick and fleshy, base cordate, margins deeply crenate, eciliate or sparsely short glandular-ciliate, surfaces glabrous or ± hairy. Inflorescences 10+-flowered, ± open, lax to congested, conic, sometimes also glomerate thyrses, 10–35 cm, tangled-hairy (pilose-arachnoid) at least distally, sometimes also purple- or brown-tipped stipitate-glandular. Flowers: sepals reflexed, ± ovate; petals white to pinkish, rarely orange-spotted, ovate to oblong, narrowly to broadly clawed, 2.5–4.5 mm, longer than sepals; filaments distinctly club-shaped; pistils connate 1/2–3/4 their lengths; ovary superior (to 1/3 adnate to hypanthium). Capsules green to yellow and purplish tinged to dark purple, valvate.
Alta., B.C., N.W.T., Nunavut, Yukon, Alaska, Oreg., Wash., Europe (ne Russia), Asia.
Varieties 6 (5 in the flora).
Although sometimes reported for North America, Saxifraga nelsoniana var. aestivalis (Fischer & C. A. Meyer) H. Ohba (S. aestivalis Fischer & C. A. Meyer) is found only in Eurasia.
|1||Inflorescences purple- or brown-tipped stipitate- glandular.||Micranthes nelsoniana var. nelsoniana|
|1||Inflorescences tangled-hairy||> 2|
|2||Leaf blade margins 9-12-toothed; capsules 6-12 mm; mostly Queen Charlotte Islands, adjacent coastal British Columbia.||Micranthes nelsoniana var. carlottae|
|2||Leaf blade margins 12-18-toothed; capsules 3-8 mm; Oregon to Alaska and nw Canada||> 3|
|3||Inflorescences somewhat lax, hairs appressed; Coast Ranges and Cascades, British Columbia, Oregon, Washington.||Micranthes nelsoniana var. cascadensis|
|3||Inflorescences congested, hairs ascending; nw Canada, Alaska||> 4|
|4||Leaf blades thick, fleshy; pistils connate most of their lengths; Aleutian Islands, Alaska.||Micranthes nelsoniana var. insularis|
|4||Leaf blades thin, not fleshy; pistils connate to 3/4 their lengths; nw Canada, Alaska.||Micranthes nelsoniana var. porsildiana|