Pellaea intermedia |
Pellaea glabella |
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creeping cliff brake, intermediate cliffbrake |
pelléade glabre, simple cliff-brake, slender cliff-brake, smooth cliff-brake, smooth cliffbrake fern |
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Stems | creeping, horizontal, slender, 2–4 mm diam.; scales mostly bicolored, narrowly lanceolate, largest scales 0.3–0.8 mm wide, centers black, thick, margins brown, thin, irregularly dentate. |
compact, ascending, stout, 5–10 mm diam.; scales uniformly reddish brown, linear-subulate, 0.1–0.3 mm wide, thin, margins sinuous, entire to denticulate. |
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Leaves | monomorphic, widely scattered along stem, 12–50 cm; croziers pubescent and bearing a few scales. |
monomorphic, clustered on stem, 2–40 cm; croziers sparsely villous. |
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Petiole | straw-colored, tan, or gray, not lustrous, rounded or slightly flattened adaxially, without prominent articulation lines. |
brown, lustrous, rounded adaxially, occasionally with prominent articulation lines near base. |
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Blade | ovate to elongate-deltate, usually 2-pinnate proximally, 4–20 cm wide; rachis tan throughout, straight to slightly flexuous, rounded or flattened adaxially, ± pubescent. |
linear-oblong to ovate-lanceolate, 1–2-pinnate proximally, 1–8 cm wide; rachis brown throughout, straight, rounded adaxially, nearly glabrous. |
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Ultimate segments | ovate to elliptic, 5–15 mm, leathery, glabrous or usually puberulent abaxially; margins recurved on fertile segments, usually covering less than 1/2 abaxial surface, borders whitish, nearly entire; apex obtuse to slightly mucronate. |
oblong-lanceolate, 5–20 mm, leathery to herbaceous, glabrous except for occasional hairlike scales abaxially near midrib; margins recurved on fertile segments, covering less than 1/2 abaxial surface, borders whitish, erose-denticulate; apex obtuse. |
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Pinnae | perpendicular to rachis or slightly ascending, not decurrent on rachis, usually with 7–21 ultimate segments; costae straight to slightly flexuous, 20–100 mm, longer than ultimate segments. |
somewhat ascending, decurrent on rachis, usually with 3–7 lobes or ultimate segments; costae when present straight, 1–50 mm, often shorter than ultimate segments. |
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Veins | of ultimate segments obscure. |
of ultimate segments usually obscure. |
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Sporangia | short-stalked, containing 32 spores, not intermixed with farina-producing glands. |
long-stalked, containing 32 or 64 spores, not intermixed with farina-producing glands. |
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n | = 2n = 87, 116, apogamous. |
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Pellaea intermedia |
Pellaea glabella |
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Phenology | Sporulating summer–fall. | |||||||||||||
Habitat | Rocky slopes and ledges, on a variety of substrates, including limestone and granite | |||||||||||||
Elevation | 300–2400 m (1000–7900 ft) | |||||||||||||
Distribution |
AZ; NM; TX; n Mexico
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AR; AZ; CO; CT; IA; ID; IL; IN; KS; KY; MA; MD; MI; MN; MO; MT; ND; NE; NM; NY; OH; OK; PA; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; ON; QC; SK; only in the flora
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Discussion | Plants of Pellaea intermedia in the flora are apogamous triploids and tetraploids; a sexual diploid cytotype has been found near Saltillo, Mexico (A. F. Tryon 1968). Given the high degree of morphologic similarity among the three cytotypes, the North American polyploids probably were derived from the Mexican diploid through autopolyploidy. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Pellaea glabella includes four geographically and genetically isolated taxa treated here as subspecies. D. B. Lellinger (1985) recognized three species in this difficult group, but isozyme analyses (G. J. Gastony 1988) showed that one of these (P. suksdorfiana) is an autotetraploid derivative of the diploid known as P. occidentalis. As a result, Gastony recognized just two species: P. glabella (with two varieties) and P. occidentalis (with two subspecies). The few morphologic features that distinguish these taxa, however, are subtle and environmentally plastic, and the isozyme data indicate that they are less divergent genetically than any other pair of Pellaea species in North America. Therefore, a more conservative taxonomic treatment seems warranted. Subspecies 4. (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. | ||||||||||||
Parent taxa | Pteridaceae > Pellaea | Pteridaceae > Pellaea | ||||||||||||
Sibling taxa | ||||||||||||||
Subordinate taxa | ||||||||||||||
Synonyms | P. intermedia var. pubescens | |||||||||||||
Name authority | Mettenius ex Kuhn: Linnaea 38: 84. (1869) | Mettenius ex Kuhn: Linnaea 36: 87. (1869) | ||||||||||||
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