9. Notholaena copelandii C. C. Hall, Amer. Fern J. 40: 181, plate 16. 1950.
Cheilanthes candida M. Martens & Galeotti var. copelandii (C. C. Hall) Mickel; Chrysochosma candida (M. Martens & Galeotti) Kümmerle var. copelandii (C. C. Hall) Pichi-Sermolli; Notholaena candida (M. Martens & Galeotti) Hooker var. copelandii (C. C. Hall) R. M. Tryon
Stem scales strongly bicolored, margins brown, broad and well defined, thin, weakly ciliate. Leaves 6--25 cm. Petiole black, equal to or somewhat longer than blade, rounded adaxially, glabrous except for a few scales and farinose glands near base. Blade ovate, 2-pinnate-pinnatifid, 1--2 times longer than wide, abaxially with conspicuous white farina, scales absent, adaxially glandular; basal pinnae much larger than adjacent pair, strongly inequilateral, proximal basiscopic pinnules greatly enlarged. Ultimate segments sessile, broadly adnate to costae; segment margins slightly recurved, rarely concealing sporangia. Sporangia containing 64 spores. 2 n = 60.
Sporulating summer--fall. Rocky slopes and cliffs, apparently confined to limestone; 300--1500 m; Tex.; Mexico.
Notholaena copelandii often has been treated as a variety of the Mexican species N . candida (M. Martens & Galeotti) Hooker. The two taxa show significant differences in stem scale and leaf morphology (R. M. Tryon 1956), density of glands on the adaxial leaf surface, and chemical composition of the farinose indument (E. Wollenweber 1984). Measures of genetic similarity based on isozyme data indicate that N . copelandii and N . candida are quite distinct and, at present, allopatry precludes gene flow. Past hybridization may account for the small number of intermediate specimens reported from San Luis Potosí, Mexico, by R. M. Tryon (1956).