Pellaea intermedia |
Pellaea |
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creeping cliff brake, intermediate cliffbrake |
cliff-brake |
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Habit | Plants usually on rock. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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 to long-creeping, ascending to horizontal, usually branched; scales brown to tan or often bicolored with dark, central stripe and lighter margins, linear-subulate to lanceolate (rarely ovate), margins dentate, erose, or entire. |
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Leaves | monomorphic, widely scattered along stem, 12–50 cm; croziers pubescent and bearing a few scales. |
monomorphic to somewhat dimorphic, clustered to widely scattered, 2–100 cm. |
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Petiole | straw-colored, tan, or gray, not lustrous, rounded or slightly flattened adaxially, without prominent articulation lines. |
brown, black, straw-colored, or gray, rounded, flattened or with single longitudinal groove adaxially, glabrous or pubescent, usually with a few scales at base, with single vascular bundle. |
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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 to ovate-deltate, 1–4-pinnate proximally, leathery or rarely somewhat herbaceous, abaxially glabrous, pubescent, or with hairlike scales scattered along costae, adaxially usually glabrous, dull, not striate; rachis straight or flexuous. |
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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. |
of blade usually stalked and free from costae, elliptic, lanceolate to linear, usually more than 4 mm wide; base rounded, truncate, or cordate; stalks often lustrous and dark colored; segment margins reflexed to form confluent, poorly defined, false indusia extending entire length of segment. |
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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. |
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Veins | of ultimate segments obscure. |
of ultimate segments free or rarely anastomosing, usually obscure, pinnately branched and divergent distally. |
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False indusia | greenish to whitish, narrow, clearly marginal, often concealing the sporangia. |
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Sporangia | short-stalked, containing 32 spores, not intermixed with farina-producing glands. |
scattered along veins near segment margins, containing 32 or 64 spores, often intermixed with glands, farina-producing. |
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Spores | brown to tan (rarely yellow), tetrahedral-globose, rugose or cristate, lacking prominent equatorial ridge. |
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n | = 2n = 87, 116, apogamous. |
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x | = 29. |
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Pellaea intermedia |
Pellaea |
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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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Most in the Western Hemisphere; a small number in Asia; Africa; the Pacific Islands; and Australia |
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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 in the broad sense is a diverse, poorly defined assemblage of xeric-adapted ferns (A. R. Smith 1981). Relationships among the North American, neotropical, and Eastern Hemisphere species are unclear, and it seems likely that the genus, as broadly construed by E. B. Copeland (1947) and R. M. Tryon and A. F. Tryon (1982), is polyphyletic. The species included here in Pellaea belong to a closely knit alliance that is usually recognized as a distinct section (sect. Pellaea). Although the inclusion of P. bridgesii in this group has been questioned (A. F. Tryon 1957), W. H. Wagner Jr. et al. (1983) have shown that the aberrant morphology of this species is simply an extreme expression of evolutionary trends commonly encountered in sect. Pellaea. Among Western Hemisphere cheilanthoid ferns, species of Pellaea show clear morphologic, chromosomal, and biochemical affinities to Argyrochosma and members of the Cheilanthes alabamensis complex. In fact, the glabrous species of Argyrochosma (A. jonesii and A. microphylla) are commonly misidentified as Pellaea. These species are easily recognizable, however, because they have a combination of concolored stem scales and small ultimate segments (less than 4 mm wide). Species ca. 40 (15 in the flora). (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 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | P. intermedia var. pubescens | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | Mettenius ex Kuhn: Linnaea 38: 84. (1869) | Link: Fil. Spec. 59. (1841) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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