Plants of Cheilanthes alabamensis occurring in the flora are apogamous triploids; a sexual diploid cytotype has been found in Nuevo León, Mexico (M. D. Windham, unpublished). Given the high degree of morphologic similarity between the two cytotypes, the North American triploid probably was derived from the Mexican diploid through autopolyploidy. In the flora, Cheilanthes alabamensis is most often confused with C . microphylla , from which it is distinguished by having thicker stems, mostly green costae, and 32-spored sporangia.