Xaxim (Dicksonia sellowiana) also known by the names of Samambaia-açu and Samambaia Imperial, is native to the Atlantic Forest in Southwest Brazil. It is cylindrical, and up to 2 meters. Due to rampant extraction for use in cultivation of other plants, the species is endangered and its extraction is prohibited in Brazil. The Dicksoniaceae is a family of tropical, subtropical and warm temperate ferns. Most of the 5-6 genera in the family are terrestrial ferns or have very short trunks compared to tree ferns of the family Cyatheaceae. However, some of the larger species can reach several metres in height.  The ferns of family Dicksoniaceae are generally regarded as more primitive than those of the family Cyatheaceae, having originated in the early Jurassic period. Only 3 extant genera are recognised in this monophyletic family:
* Calochlaena
* Dicksonia
* Lophosoria