[2][3] The stipe (the stalk of the leaf, below the blade) is 3 to 16 centimeters (1.2 to 6.3 in) long[4] and typically about one-quarter to one-third of the total length of the frond.

[4] The rachis (leaf axis) is rounded on the upper side, dark brown in color, and bears soft hairs of uniform shape, and linear-lanceolate scales.

(This character distinguishes the species from the very similar Myriopteris tomentosa, where the scales of the costa are linear and appear hairlike except on close examination.

[3]The upper surface of the leaf may bear abundant fine, white to rusty, unbranched curly hairs 0.5 to 1 millimeter (0.020 to 0.039 in) long, or they may be sparse to almost entirely absent.

Reproduction is apogamous: triploid spores are formed by mitosis, rather than meiosis, and grow into gametophytes, which sprout a genetically identical sporophyte without fertilization.

[6][7] Material placed in C. castanea (with a relatively hairless upper surface) has been confused with M. gracillima, but the latter is smaller and has narrower scales underneath with long cilia.

[11] In 1867, John Gilbert Baker (who noted that he had not yet seen specimens of M. rufa), described a new species, Cheilanthes eatonii, based on material gathered by Charles Wright on an 1849 expedition through Texas.

[13] By a strict application of the principle of priority, Oliver Atkins Farwell transferred C. eatonii to the genus Allosorus as A. lindheimeri var.

Eaton did not explain his choice of epithet, meaning "light reddish-brown",[16] but it may refer to the color of the matted hairs on the underside of the leaf, which he described as "bright-ferrugineous" (rusty).

He noted that it was, in fact, very similar to C. eatonii, but with much reduced or absent hair on the upper surface, replaced by stellate, linear scales, and somewhat larger and more separate leaf segments.

[18] He named it Cheilanthes castanea, an epithet meaning "chestnut-brown",[19] perhaps a reference to the "glossy, dark brown" color of the scales.

Doctoral work by Timothy Reeves in 1979 found many intermediates between C. castanea and C. eatonii, and he preferred to treat them as a single species, a position followed by Flora of North America in 1993.

Convergent evolution in arid environments is thought to be responsible for widespread homoplasy in the morphological characters traditionally used to classify it and the segregate genera that have sometimes been recognized.

On the basis of molecular evidence, Amanda Grusz and Michael D. Windham revived the genus Myriopteris in 2013 for a group of species formerly placed in Cheilanthes.

[26] Myriopteris rufa occurs in the southwestern United States from Arkansas (historically) and Texas and Oklahoma west to Arizona and Utah,[27] and south through northern and eastern Mexico to Vera Cruz.

[28] Populations in northeast Texas are disjunct and occur in isolated rocky habitats, several of them described by Correll, who collected from them, as "iron ore rocks".