Pellaea ternifolia
Pellaea ternifolia subsp. arizonica
trans-Pecos cliffbrake
Arizonia 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.
monomorphic, clustered on stem, 10–50 cm;
croziers sparsely to densely villous.
black or dark purple, lustrous, rounded or slightly flattened adaxially, without prominent articulation lines.
rounded or slightly flattened adaxially in distal portion;
rachis glabrous or with a few widely scattered hairs;
pinnae completely glabrous;
largest ultimate segments (excluding terminal pinnae) usually more than 18 mm;
spores averaging 46–53 µm diam. 2n = 116.
linear to ovate, deeply pinnate-pinnatifid proximally, 2.5–8 cm wide;
rachis black or purple throughout, straight, often flattened adaxially, glabrous or villous.
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.
perpendicular to rachis or slightly ascending, not decurrent on rachis, ternate at base of leaf;
costae absent.
of ultimate segments obscure.
long-stalked, containing 64 spores, not intermixed with farina-producing glands.
Pellaea ternifolia
Pellaea ternifolia subsp. arizonica
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.)
Pellaea ternifolia subsp. arizonica and P. wrightiana hybridize; the hybrids are morphologically intermediate tetraploids and have malformed spores.
(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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