Etymology From the Greek erythros meaning red; usually used as a prefix to indicate the color, thus it means having red sori.

Description Rhizome: short-creeping, subterranean.
Frond: 60 cm high by 25 cm wide, evergreen, monomorphic, blade/stipe ratio: 3:2 to 2:1.
Stipe: grooved, straw-colored, tinted red when young, scales linear to linear-lanceolate, entire at margin, brown to blackish brown, larger ones at base 1 cm, vascular bundles: two primary bundles and several smaller ones in a c-shaped pattern.
Blade: 2-pinnate, triangular, acuminate at apex, somewhat leathery, bullate scales on lower surface of costa.
Pinnae: 10 to 15 pair, lowest pair anadromic, catadromic above; pinnules lower pinnules often longer, those nearer the base and the rachis stalked and eared; costae grooved above, continuous from rachis to costae; margins crenate; veins free, forked.
Sori: round, in 1 row between midrib and margin, on the entire frond, indusium: reniform, red, attached at a sinus, sporangia: brownish, maturity: summer to fall.

Culture Habitat: forest floor in lowlands. Distribution: Honshu, Shikoku and Kyushu, Phillipines, China, Korea. Hardy to -25°C, USDA Zone 5.

Distinctive Characteristics red indusia, red new growth

Synonyms
Aspidium erythrosorum D. C. Eaton
Dryopteris cystolepidota (Miq.) C. Chr.
Lastrea erythrosora Moore
Nephrodium erythrosorum Hook.