Micranthes ferruginea |
Micranthes tenuis |
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Alaska saxifrage, rusty hair saxifrage, rusty saxifrage |
slender saxifrage |
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Habit | Plants solitary or tufted, with bulbils on caudices, short-rhizomatous. | Plants tufted, with bulbils on caudices. |
Leaves | basal; petiole indistinct, flattened, to 2 cm; blade spatulate to oblanceolate, 1–8(–10) cm, ± fleshy, base cuneate, margins irregularly serrate (usually with fewer than 12 coarse teeth), ciliate, surfaces 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 | 20–30+-flowered, (flowers sometimes replaced ± completely by bulbils, or bulbils sometimes absent), open, lax thyrses, 10–40 cm, moderately to ± densely purple stipitate-glandular; (bracts reduced). |
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 | ± bilaterally symmetric; sepals reflexed, ovate to oblong; petals white, 3 with 2 basal yellow spots, 2 without spots, elliptic to oblanceolate, clawed, 3–5 mm, longer than sepals; filaments linear, flattened; pistils connate 1/2+ their lengths; ovary superior, (to 1/3 adnate to hypanthium). |
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Capsules | green or yellow, sometimes purple tinged, or partly purple, valvate. |
reddish to purplish, folliclelike. |
2n | = 20. |
= 20. |
Micranthes ferruginea |
Micranthes tenuis |
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Phenology | Flowering summer–early autumn. | Flowering summer. |
Habitat | Wet ledges, seepage slopes, stream banks | Open, mossy tundra, rocky ridges, shady ledges |
Elevation | 10-2700 m (0-8900 ft) | 0-1500 m (0-4900 ft) |
Distribution |
AK; CA; ID; MT; OR; WA; WY; AB; BC; NT
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AK; BC; LB; NT; NU; QC; YT; Greenland; Europe; Asia (Siberia) |
Discussion | Plants with bulbils replacing flowers are more common in the southern part (southern Alberta and British Columbia southwards) of the range of Micranthes ferruginea and have been called Saxifraga ferruginea var. macounii. (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. 58. | FNA vol. 8, p. 65. |
Parent taxa | Saxifragaceae > Micranthes | Saxifragaceae > Micranthes |
Sibling taxa | ||
Synonyms | Saxifraga ferruginea, Saxifraga ferruginea var. macounii, Saxifraga ferruginea var. newcombei, Saxifraga ferruginea var. vreelandii, Saxifraga newcombei | Saxifraga nivalis var. tenuis, Saxifraga tenuis |
Name authority | (Graham) Brouillet & Gornall: J. Bot. Res. Inst. Texas 1: 1020. 2007 , | (Wahlenberg) Small: in N. L. Britton et al., N. Amer. Fl. 22: 136. (1905) |
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