Plants slender, ca. 1 mm wide measured across leafy stem, to 10 cm long. Stems freely and irregularly branched; sympodial innovations uncommon; branches often elongate and filiform. Stem leaves erect, ovate to oblong-lanceolate, moderately concave, 0.7--1.6 × 0.35--0.7 mm, narrowly decurrent, margin serrulate distally, apex acute to acuminate; cells 30--80 × 4--5 µm, prorulate here and there, shorter and broader at very base, alar cells subquadrate to oblong, 10--17 × 10 µm. Branch leaves concave, 0.3--0.75 × 0.15--0.35 mm. Inflorescences and sporophytes unknown.

Wet, shaded rocks in moist montane forests, near waterfalls or in deep ravines; 500--1700 m; N.C., S.C., Tenn.

Known from about 10 localities, Leptohymenium sharpii is endemic to the Southern Appalachian Mountains and is apparently rare. Although originally described as a variety of Hylocomium splendens, the stems and branches lack paraphyllia. Over the past thirty years Leptohymenium sharpii has been moved from one genus to another. The occasionally sympodial innovations, decurrent leaves, and prorulate leaf cells suggest that it belongs here. Finding plants with sporophytes would aid greatly in resolving generic placement of this puzzling species.