Cheilanthes horridula Maxom, prickly lip fern. Perennial herb, rhizomatous, fibrous–rooted, rosetted, with ascending leaves, in range < 15 cm tall; shoot with only basal leaves, foliage monomorphic, initially sterile later forming sporangia on lower surface, pubescent, especially short–hirsute, lacking glandular hairs; emerging leaves hooked at growing tips (not coiled, i.e., vernation not circinnate); rhizome compact to short–creeping, 4—7 mm diameter, densely covered with scales, scales persistent, the common form loosely appressed, long–acuminate or more slender and difficult to distinguish from hairs, mostly 1.5—3 × 0.1—0.4 mm, initially colorless aging first with brown cell outlines and then uniformly brown, lacking darker central stripe, with several minute teeth on margins below midpoint.
Leaves (fronds) helically alternate, odd–2–pinnately compound, with 6—10 primary leaflets per side in subopposite pairs below midblade, petiolate; petiole (stipe) cylindric, to 60 mm long, brittle, initially glossy dark red–purple aging black, initially with persistent scales mixed with shorter hairs; blade ± oblong, in range 35—120 × 15—30 mm, lateral primary leaflets ⊥ to rachis, terminal lobe triangular and ca. 5 mm long with a couple short sublobes; rachis cylindric, glossy dark red–purple aging black, lateral primary leaflets spaced < 15 mm apart, with hairs and persistent scales; petiolule ca. 1 mm long, glossy dark red–purple aging black; lateral primary leaflets ± triangular in outline, in range to 12 × 7 mm, mostly with 6—9 secondary leaflets alternate along rachilla; rachilla shallowly channeled, green or red–purple next to petiolule; secondary leaflets, sessile to subsessile, obtuse–ovate with margins inrolled (revolute) to under side (rounded at tip), mostly 3—4 × 2.5 mm, veins inconspicuous, upper surface with scattered, ascending short–hirsute hairs having thickened base, lower surface with longer hairs and lacking scales.
Sori submarginal on lower surface, appearing continuous except at tip, each secondary leaflet with many sporangia in ± 2 rows partially concealed by down–curved, nongreen, minutely crenate lobes of leaf margin (false indusium), each tooth with a short hair.
Sporangia spheroid, ca. 0.25 mm, red and translucent aging with darker spores, the dehiscence mechanism (annulus) ringlike, each sporangium with 64 spores.
A. C. Gibson