Micranthes petiolaris |
Micranthes occidentalis |
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Michaux's saxifrage |
mountain saxifrage, redwool saxifrage, western saxifrage |
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Habit | Plants solitary or tufted, with bulbils on caudices. | Plants in groups or sometimes almost mat-forming, with bulbils on caudices or rhizomatous. |
Leaves | basal; petiole somewhat flattened, 2–6 cm; blade oblanceolate, 2–12 cm, thin, basecuneate to ± attenuate, margins usually 15+-toothed (teeth large, lobelike), densely long glandular-ciliate, surfaces hairy. |
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. |
Inflorescences | 30+-flowered, very open, lax thyrses, (flowers rarely replaced by bulbils), 10–40 cm, densely tangled, purple-tipped stipitate-glandular; (bracts leaflike, gradually reduced distally). |
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). |
Flowers | slightly bilaterally symmetric; sepals reflexed, oblong to elliptic; petals white, 3 with 2 basal yellow spots, 2 without spots, oblanceolate to spatulate, clawed, 3–4.5 mm, longer than sepals; filaments linear, flattened; pistils connate 1/2+ their lengths; ovary superior. |
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. |
Capsules | green to yellow, sometimes purple tinged, valvate |
greenish or reddish to ± dark purple, folliclelike. |
2n | = 20, 38, 40, 56, 58. |
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Micranthes petiolaris |
Micranthes occidentalis |
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Phenology | Flowering late spring–early autumn. | Flowering spring–summer. |
Habitat | Wet ledges, boulderfields, and rocky slopes, usually in thin soil over rock | Wet, rocky or gravelly slopes, moist to dry alpine meadows, flushes |
Elevation | 500-2100 m (1600-6900 ft) | 500-4000 m (1600-13100 ft) |
Distribution |
GA; KY; MD; NC; SC; TN; VA; WV
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AK; ID; MT; NV; OR; SD; WA; WY; AB; BC; SK
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Discussion | Micranthes petiolaris (Rafinesque) Brouillet & Gornall is an isonym. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 8, p. 58. | FNA vol. 8, p. 62. |
Parent taxa | Saxifragaceae > Micranthes | Saxifragaceae > Micranthes |
Sibling taxa | ||
Synonyms | Hexaphoma petiolaris, Saxifraga michauxii, Saxifraga petiolaris | Saxifraga occidentalis, Saxifraga allenii, Saxifraga occidentalis var. allenii, Saxifraga occidentalis var. wallowensis, Saxifraga reflexa subsp. occidentalis, Saxifraga saximontana |
Name authority | (Rafinesque) Bush: Amer. Midl. Naturalist 11: 225. 1928 , | (S. Watson) Small: in N. L. Britton et al., N. Amer. Fl. 22: 144. 1905 , |
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