ALIEN FERNS IN HAWAI'I

Macrothelypteris torresiana (Gaudichaud) Ching [syn. Lastrea torresiana (Gaudichaud) Moore; Dryopteris uliginosa (Kunze) C. Christensen], Wood Fern, a widespread invader from the Old World, has been collected on all the islands save Moloka'i, where it may simply have been overlooked. Native to the tropical and subtropical regions of Asia and Africa, this invasive species has extended its range throughout the Pacific and has colonized the New World from the southeastern U.S. to northern Argentina and the Caribbean. Wagner reported that it was first noted as naturalized in Hawai"i in 1892. The earliest specimens I have seen from Hawai'i was made in 1915 (Forbes 606.H, BISH), although Maxon (1928) cited a collection from O'ahu in 1908. Wagner anticipated that this species would spread throughout the island forests since it was already well established in scattered areas, a prediction that certainly has been borne out.