Gymnosphaera metteniana, synonyms Alsophila metteniana and Cyathea metteniana, is a species of tree fern native to the Ryukyu Islands, Japan, Taiwan, and southern China,[2] where it grows in wet forest, forest margins, and on hillsides.

The trunk of this plant is erect, up to 1 m tall, and 6–10 cm in diameter.

It is covered in long, broad-based scales that are usually bicoloured (glossy brown with a paler margin).

Sori are round, lack indusia, and occur in two rows, one on either side of the pinnule midvein.

[3] The specific epithet metteniana commemorates pteridologist Georg Heinrich Mettenius (1823-1866), who named several Cyathea species.