Dryopteris amurensis ("Okuyamashida")

Japanese name: オクヤマシダ
Scientific name: Dryopteris amurensis

A summer-green fern seen in forests of the subalpine zone, often growing in colonies.
It has a creeping rhizome.

The stipe is 20–50 cm long, longer than the blade, and straw-colored.
The scales on the stipe are rather sparse, broadly ovate to ovate, 3–7 mm long, pale brown and membranous.
The fronds are herbaceous, 15–25 cm long, and rather broadly pentagonal-broadly ovate, deeply tripinnately divided, with the lower parts tripinnately compound.
The pinnae have short stalks, and the lowest pinna is triangular-ovate and markedly larger than the second one.
The pinnules are oblong to ovate-oblong, deeply to fully pinnately divided, with deep, sharp serrations whose tips extend into awns.
Small sac-shaped scales are sparsely attached to the axes of the pinnules.
Narrow scales are sparsely attached to the rachis and the pinna axes.
The sori are small and are borne midway between the midrib and the margin of the segments; the indusium is about 0.7 mm in diameter and entire.

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