noun
1. : any of various ferns exhibiting an arborescent habit with a caudex that is woody and elongated, belonging chiefly to the families Cyatheaceae and Marattiaceae but including some members of the Polypodiaceae, and being chiefly tropical and especially abundant in Australia and New Zealand
2. : any of several ferns that usually grow on or about trees: as
a. : gray polypody
b. : royal fern