Etymology Japonicum refers to Japan.

Description Rhizome: short-creeping, branching, short, blackish hairs.
Frond: 300 cm high , but can be much more, deciduous, somewhat dimorphic, the fertile pinnae (in upper part of frond) narrowed, blade/stipe ratio: 30:1.
Stipe: twining, pale brown, lustrous, 10-30 cm, vascular bundles: 1, a simple cylinder.
Blade: 3-pinnate or more, twining rachis, 2-pinnate pinnae, papery, short, curved hairs on both blade surfaces.
Pinnae: alternate, a pair of 2-pinnate segments, less than 20 cm long; costae densely hairy above and sparsely so below, distinctly winged; segments lanceolate, lobed; fertile segments fringed; veins free, forking, ending in marginal teeth.
Sori: , indusium: false, pear-shaped scale, sporangia: in 2 rows, below the margin, maturity: late summer to early winter.

Culture Habitat: thickets in low mountains. Distribution: Japan, Korea, China. Hardy to -15°C, USDA Zone 7.

Distinctive Characteristics twining habit

Synonyms
Ophioglossum japonicum Thunb.
Adiantum scandens Lour.
Hydroglossum japonicum (Thunb.) Willd.
Lygodium scandens (L.)Sw.