Pellaea microphylla Mettenius ex Kuhn, Linnaea 36: 86. 1869; Cheilanthes parvifolia (R. M. Tryon) Mickel; Notholaena parvifolia R. M. Tryon

Stem scales brown. Leaves 7--25 cm. Petiole brown, 0.75--1.5 mm diam. Blade deltate to ovate, 3--4-pinnate proximally, leathery, abaxially and adaxially glabrous; rachis flattened or shallowly grooved adaxially. Pinna costae straight to somewhat flexuous, branches rarely arising from prominent angles. Ultimate segments articulate, dark color of stalks stopping abruptly at segment bases; segment margins recurved to revolute, often concealing sporangia; veins obscure adaxially. Sporangia submarginal, borne on distal 1/3 of secondary veins, containing 64 spores. 2 n = 54.

Sporulating summer--fall. Rocky limestone hillsides and cliffs; 300--2100 m; N.Mex., Tex.; n Mexico.

Argyrochosma microphylla is probably the most distinctive species of Argyrochosma in the flora. Chromosome studies by I. W. Knobloch et al. (1973) suggest that it may include diploid and tetraploid cytotypes.