Micranthes nelsoniana |
Micranthes tenuis |
|||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
dotted saxifrage, heartleaf saxifrage, Nelson's saxifrage, saxifrage |
slender saxifrage |
|||||||||||||||||
Habit | Plants solitary or tufted, with bulbils on branched caudices, rhizomatous. | Plants tufted, with bulbils on caudices. | ||||||||||||||||
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. |
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 | 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. |
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; 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. |
reddish to purplish, folliclelike. |
||||||||||||||||
2n | = 20. |
|||||||||||||||||
Micranthes nelsoniana |
Micranthes tenuis |
|||||||||||||||||
Phenology | Flowering summer. | |||||||||||||||||
Habitat | Open, mossy tundra, rocky ridges, shady ledges | |||||||||||||||||
Elevation | 0-1500 m (0-4900 ft) | |||||||||||||||||
Distribution |
AK; OR; WA; AB; BC; NT; NU; YT; Europe (ne Russia); Asia
|
AK; BC; LB; NT; NU; QC; YT; Greenland; Europe; Asia (Siberia) |
||||||||||||||||
Discussion | 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. (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.) |
||||||||||||||||
Key |
|
|||||||||||||||||
Source | FNA vol. 8, p. 54. | FNA vol. 8, p. 65. | ||||||||||||||||
Parent taxa | Saxifragaceae > Micranthes | Saxifragaceae > Micranthes | ||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Synonyms | Saxifraga nelsoniana, Saxifraga punctata subsp. nelsoniana, Saxifraga punctata var. nelsoniana | Saxifraga nivalis var. tenuis, Saxifraga tenuis | ||||||||||||||||
Name authority | (D. Don) Small: in N. L. Britton et al., N. Amer. Fl. 22: 147. 1905 , | (Wahlenberg) Small: in N. L. Britton et al., N. Amer. Fl. 22: 136. (1905) | ||||||||||||||||
Web links |
|
|