Greek cysto bladder + lepis scale, referring to the bullate (puffed base) scales.
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.
Habitat: on forest floor in lowlands .
Distribution: Japan and Korea.
Hardy to -20°C, USDA Zone 6.
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."
Dryopteris nipponensis Koidz.
Dryopteris erythrosora (D. C. Eaton) Kuntze var. dilatata (Koidz.) Sugim.
Dryopteris nipponensis Koidz. var. dilatatum Koidz.
Aspidium cystolepidotum Miq.
Illustration from The Cultivated Species of the Fern Genus Dryopteris in the United States, Barbara Joe Hoshizaki and Kenneth A. Wilson, American Fern Journal, 89, 1, (1999), with permission.