Micranthes oregana |
Micranthes tenuis |
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bog saxifrage, Oregon or bogsaxifrage, Oregon saxifrage |
slender saxifrage |
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Habit | Plants solitary or in clusters, with caudex or thick, fleshy rhizomes. | Plants tufted, with bulbils on caudices. |
Leaves | basal; petiole indistinct, flattened, 3–10 cm; blade linear to oblanceolate, 6–25 cm, fleshy, base cuneate, margins serrulate to denticulate, ciliate, surfaces glabrous or sparsely hairy. |
basal; petiole broad, flattened, 0.2–1 cm; blade ± obovate to ± obtrullate, 0.5–1.5 cm, ± coriaceous, base ± attenuate to ± cuneate, margins serrate to dentate on distal 1/3–2/3, sometimes ciliate, surfaces glabrous or glabrate abaxially (rarely sparsely reddish brown-hairy). |
Inflorescences | (30–)50+-flowered, open to ± crowded, conic to cylindric thyrses, 25–125 cm, hairy proximally, yellow- to pink-tipped stipitate-glandular distally. |
usually 2–10-flowered, ± capitate cymes, sometimes solitary flowers, (1–)2–7(–11) cm, hairy or glabrous proximally, glabrate or ± purple-tipped stipitate-glandular distally. (Pedicels proximal ± elongate.) Flowers: sepals erect, ovate to deltate; petals white with purple margins, usually pink or purple tinged, not spotted, obovate to oblong, clawed, 2–3 mm, usually slightly longer than sepals; filaments linear, flattened; pistils connate to 1/2 their lengths; ovary 1/2 inferior, appearing more superior in fruit. |
Flowers | sepals reflexed, ovate to triangular; petals white, not spotted, broadly elliptic to obovate and 2 times as long as sepals, sometimes oblanceolate and equaling or shorter than sepals, clawed, 2–5 mm; filaments linear, flattened; pistils connate to 1/2 their lengths; ovary 1/2+ inferior, often appearing superior in fruit. |
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Capsules | green to reddish purple, folliclelike. |
reddish to purplish, folliclelike. |
2n | = 38, 76. |
= 20. |
Micranthes oregana |
Micranthes tenuis |
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Phenology | Flowering early spring–summer. | Flowering summer. |
Habitat | Bogs, marshes | Open, mossy tundra, rocky ridges, shady ledges |
Elevation | 100-2500 m (300-8200 ft) | 0-1500 m (0-4900 ft) |
Distribution |
CA; CO; ID; MT; NV; OR; WA; AB
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AK; BC; LB; NT; NU; QC; YT; Greenland; Europe; Asia (Siberia) |
Discussion | In both habitat and morphology, Micranthes oregana is similar to M. pensylvanica. A thorough investigation of the two species, especially the populations in Colorado that are disjunct from those in Montana, is needed to clarify relationships. The name Saxifraga integrifolia was misapplied to M. oregana by early California authors. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Micranthes tenuis is morphologically distinguished from M. nivalis only with great difficulty. D. A. Webb and R. J. Gornall (1989) claimed that chromosome number is one of the chief reasons for continuing to recognize the species and, indeed, their enumeration of morphologic differences is not entirely convincing. Occasionally, both species appear to occur in the same populations. The generally smaller size, tendency to glabrousness, fewer number of flowers, and petal color variations reasonably distinguish M. tenuis. Depauperate specimens of M. nivalis are particularly difficult to separate from M. tenuis except for their very consistent hairiness and white petals. Due to the morphologic confusion, exact distributions are difficult to assess and chromosome number reports may be doubtful (D. L. Krause and K. I. Beamish 1973). A thorough systematic study is needed. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 8, p. 67. | FNA vol. 8, p. 65. |
Parent taxa | Saxifragaceae > Micranthes | Saxifragaceae > Micranthes |
Sibling taxa | ||
Synonyms | Saxifraga oregana, Saxifraga montanensis, Saxifraga oregana var. montanensis | Saxifraga nivalis var. tenuis, Saxifraga tenuis |
Name authority | (Howell) Small: in N. L. Britton et al., N. Amer. Fl. 22: 138. 1905 , | (Wahlenberg) Small: in N. L. Britton et al., N. Amer. Fl. 22: 136. (1905) |
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