Any of various ferns (especially those of the families Cyatheaceae and Dicksoniaceae) of treelike habit with a woody stem. Many attain heights of over 50 ft (15.2 m). They are natives of humid mountain forests in the tropics and subtropics and of warm temperate regions of the Southern Hemisphere. Members of the family Cyatheaceae are very large, terrestrial ferns with trunklike, upright rhizomes; the approximately 600 species are grouped into 5 genera. Dicksoniaceae contains 3 genera and 30 species. The leaves of some species in this family may reach several metres in length.