New Mexican cliff fern

Stems compact, erect to ascending, with few to many persistent petiole bases of unequal lengths; scales mostly uniformly brown but at least some bicolored with dark central stripe and pale brown margins, narrowly lanceolate. Leaves 4--30 × 1.5--6 cm. Petiole light brown or straw-colored when mature, occasionally darker at very base, not articulate above base, relatively brittle and easily shattered. Blade linear to lanceolate, usually pinnate-pinnatifid proximally, glabrescent to sparsely glandular, never viscid; glandular hairs with thin stalks and slightly expanded tips; rachis with scattered glandular hairs and rare, hairlike scales. Pinnae ovate-deltate to elliptic, longer than wide, abruptly tapered to a rounded or broadly acute apex; largest pinnae with 3--7 pairs of closely spaced pinnules; abaxial and adaxial surfaces glabrescent to sparsely glandular, lacking nonglandular hairs or scales. Pinnules dentate, often shallowly lobed; margins nonlustrous, thin, with occasional glands, lacking cilia, with 1--2-celled translucent projections on teeth. Vein tips occasionally enlarged to form whitish hydathodes visible adaxially. Indusia of narrow, filamentous segments, these uniseriate for most of length, composed of ± isodiametric cells, usually surpassing mature sporangia. Spores averaging 44--52 µm. 2 n = 152.

Sporulating summer--fall. Cliffs and rocky slopes; usually on sandstone or igneous substrates; 300--3500 m; Ariz., Colo., N.Mex., Okla., S.Dak., Tex.

Woodsia neomexicana traditionally has been identified as W . mexicana . Both taxa are tetraploid and may share one parent (M. D. Windham 1993); W . neomexicana is separated from typical W . mexicana by its completely filamentous indusial segments, reduced glandularity, and more northerly distribution. Isozyme data suggest that W . neomexicana is an allotetraploid hybrid between W . phillipsii and the diploid progenitor of W . oregana subsp. cathcartiana (M. D. Windham 1993). As with all allopolyploids, W . neomexicana can vary in the direction of either parent, and some plants (especially those resembling W . phillipsii ) can be difficult to identify. All characters except those controlled directly by ploidy level show this tendency, and spore size remains the most dependable character for distinguishing W . phillipsii and W . neomexicana . This species hybridizes with W . oregana subsp. cathcartiana and W . phillipsii to produce sterile tetraploids and triploids, respectively.