Description from Flora of China
Rhizome erect, woody. Fronds simple pinnate, up to 60 × 15 cm or larger; pinnae 12-18 pairs; sterile pinnae linear-lanceolate, up to 10 × 1 cm, shortly stalked, articulate to rachis, margin distinctly coarsely serrate; veins free, branched several times with one group to each serration; middle pinnae fertile, or sometimes extending to apical ones; fertile pinnae reduced almost to a midrib and bearing sporangia in distinct groups.
Osmunda angustifolia is much less common than the closely related O. vachellii, differing from the latter by the distinctly toothed pinna margins. It also differs from the similar species O. banksiifolia by not having fertile pinnae at the base of the fronds.
By streams on hillsides; 300-800 m. Guangdong, Hainan, Hunan, ?Taiwan [Thailand].