tree fern

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various large tropical ferns, especially of the families Cyatheaceae and Dicksoniaceae, having a woody trunklike stem and a terminal crown of large, pinnately divided fronds.

from The Century Dictionary.

• noun One of several species of ferns that attain to the size of trees.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of many tropical plants, of the families Cyatheaceae and Dicksoniaceae, that have tall trunks topped with fronds.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any of numerous usually tropical ferns having a thick woody stem or caudex and a crown of large fronds; found especially in Australia and New Zealand; chiefly of the families Cyatheaceae and Marattiaceae but some from Polypodiaceae