Pellaea atropurpurea |
Pellaea glabella |
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pelléade à stipe pourpre, purple cliff-brake, purple-stem cliff-brake |
pelléade glabre, simple cliff-brake, slender cliff-brake, smooth cliff-brake, smooth cliffbrake fern |
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Stems | compact, ascending, stout, 5–10 mm diam.; scales uniformly reddish brown (or tan), linear-subulate, 0.1–0.3 mm wide, thin, margins entire to denticulate. |
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 | somewhat dimorphic, sterile leaves shorter and less divided than fertile leaves, clustered on stems, 5–50 cm; croziers villous. |
monomorphic, clustered on stem, 2–40 cm; croziers sparsely villous. |
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Petiole | reddish purple to nearly black, lustrous, rounded adaxially, without prominent articulation lines. |
brown, lustrous, rounded adaxially, occasionally with prominent articulation lines near base. |
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Blade | elongate-deltate, usually 2-pinnate proximally, 2–18 cm wide; rachis reddish purple throughout, straight, rounded adaxially, densely pubescent adaxially with short, curly, appressed hairs. |
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 | linear-oblong, 10–75 mm, leathery, sparsely villous abaxially near midrib; margins weakly recurved to plane on fertile segments, usually covering less than 1/2 abaxial surface, borders whitish, crenulate; 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 ascending, not decurrent on rachis, usually with 3–15 ultimate segments; costae straight, 10–100 mm, often 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 | long-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, apogamous. |
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Pellaea atropurpurea |
Pellaea glabella |
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Phenology | Sporulating summer–fall. | |||||||||||||
Habitat | Calcareous cliffs and rocky slopes, usually on limestone | |||||||||||||
Elevation | 100–2500 m (300–8200 ft) | |||||||||||||
Distribution |
AL; AR; AZ; CO; CT; DC; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; MI; MN; MO; MS; NC; NE; NJ; NM; NV; NY; OH; OK; PA; RI; SC; SD; TN; TX; UT; VA; VT; WI; WV; WY; ON; QC; Mexico; Central America in Guatemala
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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 | Contrary to D. B. Lellinger's (1985) hypothesis, isozyme data indicate that neither Pellaea glabella nor P. ternifolia was involved in the origin of this apogamous triploid. Instead, it appears that P. atropurpurea is an autopolyploid derivative of a single diploid taxon that has not yet been located. A thorough survey of spore number per sporangium in this species should be undertaken to determine whether the diploid progenitor is still extant. Collections from western Canada identified as P. atropurpurea actually represent P. gastonyi, an apogamous tetraploid produced by hybridization between P. atropurpurea and diploid populations of P. glabella. Pellaea atropurpurea has also hybridized with P. wrightiana; the hybrid is a rare apogamous pentaploid known only from western Oklahoma. Pellaea lyngholmii is the apogamous tetraploid hybrid between P. atropurpurea and P. truncata. Pellaea atropurpurea is distinguished from all these hybrids by having rachises that are densely pubescent adaxially, larger ultimate segments, and spores averaging less than 62 µm in diameter. (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 | Pteris atropurpurea, P. atropurpurea var. cristata | |||||||||||||
Name authority | (Linnaeus) Link: Fil. Spec. 59. (1841) | Mettenius ex Kuhn: Linnaea 36: 87. (1869) | ||||||||||||
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