Etymology Greek cysto bladder + lepis scale, referring to the bullate (puffed base) scales.

Description Rhizome: short-creeping.
Frond: 60 cm high by 25 cm wide, evergreen, monomorphic, blade/stipe ratio: 2:1.
Stipe: grooved, scales dull brown to black, to 10mm, vascular bundles: 3-7 in a c-shaped pattern.
Blade: 3-pinnate at base, triangular, abruptly narrowed tip, thin leathery, slightly glossy, new growth red, costae with bullate scales below.
Pinnae: 15 to 20 pair, lowest pair longest; pinnules larger ones eared on both sides, generally quite long, the second downward-pointing ones on the lower pinnae the longest; costae grooved above, continuous from rachis to costae; veins free, forked.
Sori: round, medial, indusium: reniform, pale green early (reports of reddish tints are probably erroneous), at a sinus, sporangia: brownish.

Culture Habitat: on forest floor in lowlands . Distribution: Japan and Korea. Hardy to -20°C, USDA Zone 6.

Distinctive Characteristics Flora of Japan: "similar to D. erythrosora but different in: scales on stipes blackish brown, those on rachis and pinna rachis also blackish brown, rather dense, caducous; laminae broadly ovate, abruptly acuminate at apex, basal basiscopic pinnules of lowest pinnae larger, other pinnules oblong-ovate to ovate, shallowly crenate to pinnatifid, lower ones stalked; tenderly papyraceous, not shining; sori smaller; indusia not tinted reddish."

Synonyms
Dryopteris nipponensis Koidz.
Dryopteris erythrosora (D. C. Eaton) Kuntze var. dilatata (Koidz.) Sugim.
Dryopteris nipponensis Koidz. var. dilatatum Koidz.
Aspidium cystolepidotum Miq.