Woodsia ilvensis
Woodsia obtusa
oblong woodsia, rusty cliff fern, rusty woodsia, woodsie de l'île d'elbe
blunt-lobe woodsia, blunt-lobed cliff fern, bluntlobe cliff fern, woodsie à lobes arrondis
compact, erect to ascending, with abundant persistent petiole bases of ± equal length;
scales uniformly brown, lanceolate.
compact to creeping, erect to horizontal, with few to many persistent petiole bases of unequal lengths;
scales often uniformly brown but at least some bicolored with dark central stripe and pale brown margins, narrowly lanceolate.
4.5–25 × 1.2–3.5 cm.
8–60 × 2.5–12 cm.
usually brown or dark purple when mature, articulate above base at swollen node, relatively brittle and easily shattered.
light brown or straw-colored when mature, occasionally darker at very base, not articulate above base, relatively brittle and easily shattered.
narrowly lanceolate, usually 2-pinnate proximally, lacking glands, never viscid;
rachis usually with abundant hairs and scales.
lanceolate to ovate, 2-pinnate to 2-pinnate-pinnatifid proximally, moderately glandular, rarely somewhat viscid;
many glandular hairs with thick stalks and distinctly bulbous tips;
rachis with glandular hairs and scattered, often hairlike scales.
ovate-lanceolate to deltate, longer than wide, abruptly tapered to a rounded or broadly acute apex;
largest pinnae with 4–9 pairs of pinnules;
abaxial surface with mixture of hairs and linear-lanceolate scales, adaxial surface with multicellular hairs concentrated along midrib.
ovate-deltate to elliptic, 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, lacking nonglandular hairs or scales.
of narrow, hairlike segments, these uniseriate throughout, composed of cells many times longer than wide, usually surpassing mature sporangia.
of relatively broad, nonfilamentous segments, these multiseriate throughout, composed of ± isodiametric cells, entire or glandular along distal edge, concealed by or slightly surpassing mature sporangia.
averaging 39–46 µm. 2n = 82.
averaging 35–47 µm.
entire or crenate, rarely shallowly lobed;
margins nonlustrous, thin, ciliate with multicellular hairs, lacking translucent projections.
dentate, sometimes deeply lobed;
margins nonlustrous, thin, with occasional glands, lacking cilia or translucent projections.
tips frequently enlarged to form whitish hydathodes visible adaxially.
tips usually enlarged to form whitish hydathodes visible adaxially.
Woodsia ilvensis
Woodsia obtusa
Although generally separable by the characters given in the key, shade forms of Woodsia ilvensis with a reduced number of scales and hairs are occasionally misidentified as W. alpina. The morphologic distinctions between these species are further blurred by natural hybridization, which produces the intermediate triploid known as W. × gracilis. Some of the best characters for distinguishing these taxa are spore size and morphology. Spores average less than 46 µm in W. ilvensis, more than 46 µm in W. alpina, and are malformed and abortive in W. × gracilis. Woodsia ilvensis also hybridizes with W. oregana subsp. cathcartiana to form the sterile triploid W. × abbeae (F. S. Wagner 1987).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Woodsia obtusa comprises two cytotypes that are treated here as subspecies because they show subtle morphologic and ecological distinctions and tend to have different distributions. Tetraploid populations (subsp. obtusa) are found throughout the eastern flora, commonly occurring on limestone. The diploid (subsp. occidentalis) is found near the western edge of the species range, usually on sandstone and granitic substrates. Isozyme studies suggest that subsp. obtusa may have been derived from subsp. occidentalis through autopolyploidy (M. D. Windham 1993). The westernmost collections of Woodsia obtusa (all subsp. occidentalis) come from the Wichita Mountains of Oklahoma and the Edwards Plateau of Texas. Reports of this species from the trans-Pecos region of western Texas are apparently based on misidentifications.
Subspecies 2.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Spores averaging 42-47 µm; proximal pinnules of lower pinnae usually shallowly lobed or merely dentate; blades coarsely cut and evidently 2-pinnate; stems compact to short-creeping, individual branches usually 5-10 mm diam. | subsp. obtusa |
1. Spores averaging 35-42 µm; proximal pinnules of lower pinnae usually deeply lobed or pinnatifid; blades finely cut, 2-pinnate-pinnatifid; stems short- to long-creeping, individual branches 3-5 mm diam. | subsp. occidentalis |
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