From the Greek erythros meaning red; usually used as a prefix to indicate the color, thus it means having red sori.
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.
Habitat: forest floor in lowlands.
Distribution: Honshu, Shikoku and Kyushu, Phillipines, China, Korea.
Hardy to -25°C, USDA Zone 5.
red indusia, red new growth
Aspidium erythrosorum D. C. Eaton
Dryopteris cystolepidota (Miq.) C. Chr.
Lastrea erythrosora Moore
Nephrodium erythrosorum Hook.
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.