Tripteron is from tri, three, + pteron wing.
Rhizome: erect, several to many fronds in a whorl, branching, scales oblong-ovate, brown to pale brown, to 1.3 cm long.
Frond: 70 cm high by 10 cm wide, evergreen in warmer areas, monomorphic, blade/stipe ratio: 2:1 to 4:1.
Stipe: grooved, pale green, brownish at base, old stipes persistent, rather densely clothed with broadly lanceolate, membranous, and easily-shed scales, vascular bundles: 4 or more, in an arc.
Blade: best described, perhaps, as 1-pinnate with a pair of 1-pinnate basal pinnae, in three parts, one simply pinnate larger apical pinna and a pair of smaller lateral pinnae, each pinnate, soft-textured, deep green, scales of irregular forms on lower surface.
Pinnae: 20 to 35 pair, eared upwards or outwards in the case of the basal pinnae, 12 mm wide; margins toothed; veins free, forked.
Sori: round, between midrib and margin, closer to the midrib, indusium: peltate, small, shed early, central, sporangia: yellow or brownish to black.
Habitat: forest floor in mountains.
Distribution: eastern Siberia, northeastern China, Japan, Korea.
Hardy to -25°C, USDA Zone 5.
nothing else like the expanded basal pinnae
Aspidium tripteron Kunze
Dryoteris triptera (Kunze) O. Kuntze
Ptilopteris triptera (Kunze) Hayata