Argyrochosma jonesii

It grows on calcareous rocks, and has small, finely-divided leaves with a leathery texture and dark axes connecting the leaf segments.

[6] These are in turn divided into 2 to 3 pairs[6] of orbicular (circular)[2] or deltoid to ovate pinnules, obtuse at the tip and cordate (heart-shaped) or truncate (abruptly terminating) at the base[6] and borne on a short stalk.

[9] Both Edwin Copeland and Charles Alfred Weatherby suggested in the 1940s that a group of ferns related to Notholaena nivea might represent a distinct genus of its own.

Accordingly, in 1950, Conrad Vernon Morton transferred the species to Pellaea as P. jonesii, to provide a name for it in Thomas Henry Kearney's Flowering Plants and ferns of Arizona.

[12] In 1958, Philip A. Munz, preparing a flora of California and following Copeland's opinion that Notholaena was best lumped into a broadly defined Cheilanthes, transferred it to that genus as C. jonesii.

[13] John T. Mickel, carrying out a similar program of lumping in 1979, accidentally duplicated Munz's combination.

[14] The recognition of the N. nivea group as a genus was finally addressed in 1987 by Michael D. Windham, who was carrying out phylogenetic studies of the cheilanthoids.

[16] In 2018, Maarten J. M. Christenhusz transferred the species to Hemionitis as H. jonesii, as part of a program to consolidate the cheilanthoid ferns into that genus.

[19] Argyrochosma jonesii is known in the United States from California, Arizona, Nevada, and southern Utah[20] and in Mexico from Sonora,[2] particularly within the Mojave and Sonoran Deserts.

underside of greenish-gray divided leaflet with brown stalks and empty brown capsules, lacking white powder
Argyrochosma jonesii leaflet, showing slightly curled leaf margins, exposed sporangia, and dark color entering base of leaf segments.