We don't have synonyms for treefern yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are reefer, tree fern and reefers.
(n) :
Alternative form of tree fern. [Any of many tropical ferns that have tall trunks topped with fronds, of the orders Cyatheales, Marattiales, and Osmundales, especially families Cyatheaceae, Dicksoniaceae, and Metaxyaceae in Cyatheales.]
(n) :
Alternative form of tree fern. [Any of many tropical ferns that have tall trunks topped with fronds, of the orders Cyatheales, Marattiales, and Osmundales, especially families Cyatheaceae, Dicksoniaceae, and Metaxyaceae in Cyatheales.]