Micranthes occidentalis
Micranthes lyallii
mountain saxifrage, redwool saxifrage, western saxifrage
Lyall's saxifrage, red-stem saxifrage
basal;
petiole flattened, 1–5 cm;
blade ovate to elliptic, 1.5–3.5 cm, ± fleshy, base ± attenuate to ± truncate, margins shallowly, sharply serrate, ciliate, surfaces sparsely tangled, reddish brown-hairy abaxially, glabrous adaxially.
basal;
petiole rounded to flattened, 2–10 cm;
blade spatulate to obovate, 0.8–8 cm, thin, base cuneate to slightly attenuate, margins serrate to dentate, eciliate or sparsely glandular-ciliate, surfaces abaxially glabrous, adaxially sparsely brown-hairy.
usually (10–)30+-flowered, flowers crowded into 1+ glomerules in thyrses with ascending branches, 8–30 cm, purple-tipped stipitate-glandular; (bracts glabrous or marginally glandular-ciliate).
usually 10–15-flowered, lax, cylindric thyrses, (red), (4–)7–30 cm, sparsely purple-tipped stipitate-glandular.
sepals ascending to spreading, sometimes reflexed in fruit, ovate to oblong, (surfaces glabrous);
petals white, not spotted (spots rarely present), obovate to almost round, clawed, 2–4 mm, to 1.5 times as long as sepals;
filaments linear to very slightly widened near anthers, flattened;
pistils distinct almost to base;
ovary ± superior.
sepals reflexed, oblong to elliptic;
petals white, each with 2 basal yellowish green spots, elliptic to round, clawed, 2–5.5 mm, longer than sepals;
filaments club-shaped, (to 6 mm);
pistils connate 1/2+ their lengths;
ovary superior, (to 1/3 adnate to hypanthium).
greenish or reddish to ± dark purple, folliclelike.
green to yellow, distal 1/2 purple, ± folliclelike, (basally connate).
= 20, 38, 40, 56, 58.
= ca. 56, 58.
Micranthes occidentalis
Micranthes lyallii
Micranthes occidentalis appears closely related to the little-known M. mexicana (Engler & Irmscher) Brouillet & Gornall from Chihuahua, Mexico. The latter is the only species of the genus that occurs in Mexico and not in the United States. Micranthes occidentalis is disjunct between the northern Rocky Mountains and the Cypress Hills of southeastern Alberta and southwestern Saskatchewan, and the Black Hills of South Dakota. It hybridizes with M. idahoensis where their ranges overlap.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Although they have nearly disjunct sets of populations, the subspecies of Micranthes lyallii are difficult to distinguish from each other. The more northern plants tend to be larger with wider leaves and often have been called Saxifraga lyallii subsp. or var. hultenii. Apparent hybrids with M. odontoloma occur in Alberta, British Columbia, and northern Idaho, and near Glacier National Park, Montana.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
OR, 
WA - Local Web sites:
CalFlora, CalPhotos, 
Flora NW, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
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- Encyclopedia of Life
- Wikipedia
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