Woodsia |
Woodsia scopulina |
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cliff-fern, woodsia |
cliff-fern, mountain cliff fern, Rocky Mountain woodsia, woodsia, woodsie des rochers |
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Habit | Plants usually on rock. | |||||||||||||||||||||||||||||||||||||||||||||
Stems | compact to creeping; ascending or erect (rarely horizontal), stolons absent. |
compact, erect to ascending, with few to many persistent petiole bases of unequal lengths; scales uniformly brown or bicolored with dark central stripe and pale brown margins, ovate to narrowly lanceolate. |
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Leaves | monomorphic, dying back over winter or sometimes persistent into the next season. |
9–35 × 1–8 cm. |
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Petiole | 1/5–3/4 length of blade, base not conspicuously swollen; vascular bundles 2, arranged laterally, ± round or oblong in cross section. |
usually reddish brown to dark purple proximally when mature, not articulate above base, relatively brittle and easily shattered. |
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Blade | linear to lanceolate or ovate, 1–2-pinnate-pinnatifid, gradually reduced distally to pinnatifid apex, herbaceous. |
lanceolate to linear-lanceolate, 2-pinnate proximally, moderately glandular, rarely somewhat viscid; most glandular hairs with thick stalks and distinctly bulbous tips; rachis usually with abundant glandular and nonglandular hairs. |
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Pinnae | not articulate to rachis, segment margins entire to dentate, not spiny; proximal pinnae somewhat reduced, sessile, bases usually ± equilateral; costae often shallowly grooved adaxially, grooves ± continuous from rachis to costae; indument of glandular (occasionally nonglandular) hairs on both surfaces, rarely absent. |
lanceolate-deltate to ovate, longer than wide, abruptly tapered to a rounded or broadly acute apex, occasionally attenuate; largest pinnae with 5–14 pairs of pinnules; abaxial and adaxial surfaces glandular and sparsely villous, with flattened, multicellular hairs concentrated along midribs. |
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Indusia | of filamentous or nonfilamentous segments, these multiseriate proximally, often uniseriate distally, composed of ± isodiametric cells, concealed by or slightly surpassing mature sporangia. |
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Sori | in 1 row between midrib and margin on ultimate segments, round; indusia basal, dissected into several to numerous filamentous or scalelike segments encircling sorus, persistent but often obscure in mature sori. |
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Spores | brownish, cristate, rarely rugose. |
averaging 39–57 µm. |
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Pinnules | dentate, often shallowly lobed; margins nonlustrous, thin, slightly glandular and occasionally ciliate with isolated, multicellular hairs, lacking translucent projections. |
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Vein(s) | free, simple or forked. |
tips slightly (if at all) enlarged, barely visible adaxially. |
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x | = 38, 39, 41. |
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Woodsia |
Woodsia scopulina |
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Distribution |
Mostly north temperate regions and higher elevations in the tropics |
AK; AR; AZ; CA; CO; ID; KY; MT; NC; NV; OR; SD; TN; UT; VA; WA; WV; WY; AB; BC; ON; QC; SK; YT; only in the flora
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Discussion | Woodsia is a well-marked genus; its morphology and chromosome base number (x = 41) provide evidence of relationships to the dryopteroid ferns. Most authors consider Cystopteris to be its closest ally, and the two genera are often confused in herbarium collections. The resemblance is superficial in many ways, however, and Woodsia is easily distinguished from Cystopteris by its persistent petiole bases, multilobed indusia, and obscure veins that end in hydathodes before reaching the leaf margin. The North American species of Woodsia fall into two natural groups that might be recognized as subgenera. Woodsia ilvensis, W. glabella, and W. alpina have articulate petioles, indusial segments that are uniseriate throughout and composed of cells that are much longer than wide, entire or crenate pinnules, strictly concolored stem scales, and chromosome base numbers of 39–41. They are circumboreal in distribution and show clear affinities to species found only in Eurasia. The remainder of the North American taxa have petioles that are not articulate, indusial segments that are multiseriate at the base and composed of cells that are isodiametric or slightly longer than wide, dentate pinnules, often bicolored stem scales, and a chromosome base number of 38. All of these species are endemic to the New World and probably represent a distinct lineage within the genus. Hybridization is common within these natural groups, but intergroup hybrids are relatively rare. Species ca. 30 (10 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Woodsia scopulina shows substantial variation in leaf size, shape, and dissection, and in the abundance of multicellular hairs on the pinnae. Although much of this variation seems to be environmentally induced, recent studies (M. D. Windham 1993) have identified three chromosomal/morphologic variants that are treated here as subspecies. Diploid populations of W. scopulina are divisible into two groups, one of which (subsp. scopulina) is scattered throughout the mountainous regions of western North America while the other (subsp. appalachiana) is confined to montane habitats in the southeastern United States. These taxa seem amply distinct (T. M. C. Taylor 1947) and might be considered separate species if not for the existence of populations in the Great Lakes region and western cordillera that tend to bridge the morphologic and geographic gap between them. These intermediate populations (subsp. laurentiana) appear to be uniformly tetraploid and may have arisen through ancient hybridization between subsp. scopulina and subsp. appalachiana. In regions where subsp. laurentiana is sympatric with subsp. scopulina, the two taxa are rarely found growing together, suggesting that they differ in their ecological tolerances and/or habitat requirements. Subspecies 3. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 2. | FNA vol. 2. | ||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | W. obtusa var. lyallii, W. oregana var. lyallii | |||||||||||||||||||||||||||||||||||||||||||||
Name authority | R. Brown: Prodr. 158. (1810) | D. C. Eaton: Canad. Naturalist & Quart. J. Sci. 2: 91. (1865) | ||||||||||||||||||||||||||||||||||||||||||||
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