Pellaea ternifolia
Pellaea intermedia
trans-Pecos cliffbrake
creeping cliff brake, intermediate cliffbrake
compact, ascending, stout, 5–10 mm diam.;
scales bicolored, linear-subulate, 0.1–0.3 mm wide, centers black, thick, margins brown, thin, erose-dentate.
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.
monomorphic, clustered on stem, 10–50 cm;
croziers sparsely to densely villous.
monomorphic, widely scattered along stem, 12–50 cm;
croziers pubescent and bearing a few scales.
black or dark purple, lustrous, rounded or slightly flattened adaxially, without prominent articulation lines.
straw-colored, tan, or gray, not lustrous, rounded or slightly flattened adaxially, without prominent articulation lines.
linear to ovate, deeply pinnate-pinnatifid proximally, 2.5–8 cm wide;
rachis black or purple throughout, straight, often flattened adaxially, glabrous or villous.
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, 10–40 mm, leathery, glabrous to sparsely villous abaxially on midrib;
margins recurved on fertile segments, rarely covering more than 1/2 abaxial surface, borders whitish, entire;
apex mucronate.
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.
perpendicular to rachis or slightly ascending, not decurrent on rachis, ternate at base of leaf;
costae absent.
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.
of ultimate segments obscure.
of ultimate segments obscure.
long-stalked, containing 64 spores, not intermixed with farina-producing glands.
short-stalked, containing 32 spores, not intermixed with farina-producing glands.
= 2n = 87, 116, apogamous.
Pellaea ternifolia
Pellaea intermedia
Subspecies 3 (3 in the flora).
Pellaea ternifolia is represented in the flora by three morphologically and chromosomally distinct taxa. These discrete genetic entities also show a tendency toward geographic isolation and are treated here as subspecies. Diploid populations referred to P. ternifolia subsp. ternifolia are scattered from Texas through Mexico to South America. The pubescent tetraploid (P. ternifolia subsp. villosa) follows the Sierra Madre Oriental from Puebla, Mexico, north to Texas; the glabrous tetraploid (P. ternifolia subsp. arizonica) occurs in Arizona, Texas, and northern Mexico. Isozyme and chromosome studies suggest that both tetraploids are segmental allopolyploids produced by hybridization between subsp. ternifolia and other (as yet unidentified) diploid elements within P. ternifolia.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
1. Rachises villous, especially in axils of pinnae; pinnae with hairs scattered along main veins abaxially. | subsp. villosa |
1. Rachises glabrous or with a few widely scattered hairs; pinnae completely glabrous. | → 2 |
2. Largest ultimate segments (excluding terminal pinnae) usually less than 18 mm; distal portion of petioles grooved or flattened adaxially; spores usually 39–45 µm diam. | subsp. ternifolia |
2. Largest ultimate segments (excluding terminal pinnae) usually more than 18 mm; distal portion of petioles rounded or slightly flattened adaxially; spores usually 46–53 µm diam. | subsp. arizonica |
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