Etymology From the Latin Crassus, thick + the Greek rhizoma, mass of roots. But remember that a rhizome is an underground stem.

Description Rhizome: stout, 10 cm across, erect, bearing more than ten ascending fronds in a beautiful whorl, scales lanceolate to linear, larger ones more than 4 cm long.
Frond: 100 cm high by 20 cm wide, deciduous, monomorphic, blade/stipe ratio: 4:1.
Stipe: grooved, straw colored, densly scaly, lanceolate to linear, brown, lustrous, vascular bundles: 3-7 in a c-shaped pattern.
Blade: almost 2-pinnate, deltate-ovate to lanceolate, widest at the middle, herbaceous , linear to ovate scales below, absent above.
Pinnae: catadromous; costae grooved above, continuous from rachis to costae; segments oblong, rounded; margins crenate; veins free, forked, immersed on upper surface.
Sori: round, confined to upper pinnae, indusium: reniform, at a sinus, sporangia: brownish.

Culture Habitat: wooded slopes. Distribution: Japan, Korea, Manchuria, ne Asia. Hardy to -25°C, USDA Zone 5.

Synonyms
Dryopteris filix-mas (L.) Schott, misapplied
Dryopteris buschiana Fomin
Dryopteris setosa Kudo