Gymnosphaera denticulata, synonyms Alsophila acaulis, Alsophila denticulata and Cyathea hancockii, is a species of tree fern native to Japan, the Ryukyu Islands, Taiwan, southern China, Hong Kong, and Hainan.

The specific epithet hancockii commemorates William Hancock (1847-1914), who collected numerous plants in Japan, China and Southeast Asia.

[2] The trunk of the Gymnosphaera denticulata plant is either prostrate or short and erect.

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

This species may survive light frosts, but should ideally be grown in rich humus and under shelter.