Roots not proliferous. Stems ascending to erect, rarely branched; scales dark brown to blackish throughout, narrowly deltate, 2--4 × 0.25--0.45 mm, margins entire. Leaves weakly subdimorphic, fertile leaves taller and more erect than sterile leaves. Petiole reddish or purplish brown throughout, lustrous, 1--10 cm, 1/5--1 times length of blade; indument of dark brown to black scales, narrowly deltate at very base, grading into hairs distally. Blade highly variable and typically irregularly shaped, narrowly deltate to lanceolate, pinnatifid or 1-pinnate in proximal 1/3, 2--20 × 1--6(--13) cm, medium thick, sparsely pubescent adaxially only; base ± truncate; apex acute to long-attenuate, apical buds borne occasionally but not known to root in nature. Rachis reddish or purplish brown abaxially, fading to green distally, lustrous, glabrous. Pinnae in 0--3 pairs, often irregular in size and shape, deltate to narrowly deltate; proximal pinnae 5--30(--80) × 3--10(--15) mm; base truncate to obtuse, auriculate on both sides; margins entire to finely serrate or crenulate; apex obtuse to acute or occasionally attenuate. Veins somewhat evident, mostly free, rarely anastomosing. Sori 1--10(--15+) pairs per pinna, on both acroscopic and basiscopic lobes. Spores malformed (sterile form) or 64 per sporangium (fertile form). 2 n = 72, 144. Conglomerate boulders; 70 m; Ala. The above description applies to the sterile hybrid Asplenium platyneuron × rhizophyllum and its allopolyploid derivative. The allotetraploid form is known only from Hale County, Alabama, where it occurs with A . platyneuron (but not with A . rhizophyllum ) on conglomerate boulders (K. S. Walter et al. 1982). The sterile diploid form of A . ebenoides occurs at elevations of 70 to 500 m within the region where the ranges of the parental species overlap, always occurring with both parents on limestone, sandstone, or other rock strata. A hybrid between the allopolyploid and A . platyneuron [ A . × boydstoniae (K. S. Walter) J. W. Short] was discovered at Havana Glen. An unnamed hybrid between the sterile diploid (presumably via unreduced spores) and A . rhizophyllum is known from West Virginia and Missouri (K. S. Walter et al. 1982).