Pellaea intermedia
Pellaea gastonyi
creeping cliff brake, intermediate cliffbrake
Gastony's cliff-brake, Gastony's cliffbrake fern
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 entire to denticulate.
monomorphic, widely scattered along stem, 12–50 cm;
croziers pubescent and bearing a few scales.
somewhat dimorphic, sterile leaves shorter than fertile leaves, clustered on stem, 8–25 cm;
croziers villous.
straw-colored, tan, or gray, not lustrous, rounded or slightly flattened adaxially, without prominent articulation lines.
reddish purple to dark brown, lustrous, rounded adaxially, without prominent articulation lines.
ovate to elongate-deltate, usually 2-pinnate proximally, 4–20 cm wide;
rachis tan throughout, straight to slightly flexuous, rounded or flattened adaxially, ± pubescent.
elongate-deltate to lanceolate, 2-pinnate proximally, 3–6 cm wide;
rachis purple or brown throughout, straight, rounded adaxially, sparsely villous with long, divergent hairs.
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, 7–30 mm, leathery, sparsely villous abaxially near midrib;
margins usually recurved on fertile segments, covering less than 1/2 abaxial surface, borders whitish, crenulate;
apex obtuse to slightly mucronate.
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.
ascending or perpendicular to rachis, not decurrent on rachis or obscurely so, usually with 3–7 ultimate segments;
costae straight, 2–30 mm, usually shorter than ultimate segments.
of ultimate segments obscure.
of ultimate segments obscure.
short-stalked, containing 32 spores, not intermixed with farina-producing glands.
long-stalked, containing 32 spores, not intermixed with farina-producing glands.
= 2n = 87, 116, apogamous.
Pellaea intermedia
Pellaea gastonyi
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 gastonyi is an apogamous tetraploid that has originated through repeated hybridization between P. atropurpurea and P. glabella. Isozyme studies (G. J. Gastony 1988) indicate that P. glabella subsp. missouriensis was the diploid parent of plants found in Missouri, whereas diploid P. glabella subsp. occidentalis was involved in the origin of P. gastonyi populations occurring in western North America. Pellaea gastonyi is most often confused with P. atropurpurea, from which it differs in having sparsely villous rachises, smaller ultimate segments, and spores averaging more than 62 µm in diameter.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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