Japan Flora: Plant nearly glabrous; rhizomes slender, 0.5-1 mm. across, with dark brown lustrous jointed hairs, remotely leaved; fronds 10-20 cm. long; stipes 4-7 cm. long, winged; blades more or less 3-angled, narrowly ovate to broadly lanceo­late, 8-15 cm. long, 3-6 cm. wide, the rachis narrowly winged; pinnae bipinnatiparted; pinnules linear, usually 0.5-0.7 mm. wide, obtuse; indusia 1.2-1.5 mm. long, exserted, tubular, nar­rowed at base, the mouth somewhat dilated and truncate.                       

Honshu (Awa, Izu Isis, and westw.), Shikoku, Kyushu; rather common. Ryukyus and Formosa.

var. nipponica (Nakai) H. Ito. Rhizomes 0.2-0.5 mm. across; fronds 5-10 cm. long; blades 3-8 cm. long. Hok­kaido, Honshu, Kyushu. Korea (Quelpaert Isl).

var. naseana (Christ) H. Ito. Rhizomes 1-1.5 mm. across; fronds 20-40 cm. long; blades 15-30 cm. long; indusia tubular, not distinctly constricted or dilated above, 1.5-2 mm. long. Honshu (Izu and Kii Prov.), Kyu­shu. Ryukyus and Formosa. The typical variety is pantropic.