Roots not proliferous. Stems erect, unbranched; scales black throughout, linear-lanceolate, 4--5 × 0.2--0.6 mm, margins entire. Leaves monomorphic. Petiole black throughout, lustrous, 1.5--3(--5) cm, 1/4--1/10 length of blade; indument of blackish brown, filiform scales. Blade linear to narrowly oblanceolate, 1-pinnate throughout, 9--20(--30) × 1--2(--2.5) cm, thick, glabrous; base gradually tapered; apex acute, not rooting. Rachis black throughout, lustrous, glabrous. Pinnae in 20--40 pairs, oblong; medial pinnae (5--)10--20 × (2--)3--5 mm; base usually with an acroscopic auricle; margins ± entire to shallowly crenate; apex obtuse. Veins free, obscure. Sori 2--5 pairs per pinna, on both basiscopic and acroscopic sides, often confluent with age. Spores 32 per sporangium. n = 2 n = 108 (apogamous). Cliffs, sinkholes, on limestone or other basic rocks; 100--1500 m; Ala., Ariz., Ark., Del., Fla., Ga., Ill., Kans., Ky., La., Md., Miss., Mo., N.Mex., Nev., N.C., Okla., Pa., Tenn., Tex., Utah, Va., W.Va.; Mexico; West Indies in Hispaniola, Jamaica; Central America in Guatemala; South America. Asplenium parvulum M. Martens & Galeotti is an older, but illegitimate, name because it is a later homonym of A . parvulum Hooker. In Florida Asplenium resiliens hybridizes with A . heterochroum Kunze (4 x ), producing A . × heteroresiliens (5 x ).
General: Erect unbranched stems from short roots with dull black scales, linear-lanceolate 4-5 mm by 0.2-0.6 mm, with entire margins. Leaves: Monomorphic with lustrous black petiole, 1.5-3 cm; blade 9-20 cm long by 1-2 cm wide, broadly linear with pinnae in 20-40 pairs, oblong thickish and firm to leathery, entire, crenate or shallowly serrate, opposite on the rachis or nearly so, sessile, 10-20 mm by 3-5 mm; base of pinnae bears an auricle facing the tip or apex. Sporangia: Sori in 2-5 pairs per pinnae, on both the basal side and toward the tip, 32 spores per sporangium. Ecology: Found along cliffs or at the base of boulders in shaded crevices, often on granitic or limestone substrates from 2,000-8,500 ft (610-2191 m). Notes: Distinguished from other Asplenium by the short stiff pinnae and the auricle at the base of each pinnae. Etymology: Asplenium is from Greek a, without and spleen, while resiliens is from the Latin resilire, to rebound or recoil. Sources: FNA 1993, Dittmer 1954, Yarborough and Powell 2002, Kearney and Peebles 1969