Gymnosphaera metteniana, synonyms Alsophila metteniana and Cyathea metteniana, is a species of tree fern native to the Ryukyu Islands, Japan, Taiwan, and southern China, where it grows in wet forest, forest margins, and on hillsides.
The trunk of this plant is erect, up to 1 m tall, and 6âÂÂ10 cm in diameter. G. metteniana has tripinnate fronds that are 1âÂÂ2.5 m long. The stipe is brown to purple-black in colouration. 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.
The specific epithet metteniana commemorates pteridologist Georg Heinrich Mettenius (1823-1866), who named several Cyathea species.