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Invasive ferns

March 2003. A shipment of cut flowers into Palau included ferns with sporangia and the question was, are there species of ferns with potential to invade natural ecosystems. Are there any risks?

The PIER website has the following ferns listed as potentially invasive:

Azolla filiculoides Lam. azolla, Large mosquito fern
Azolla pinnata R. Br. Mosquito fern, Ferny azolla, Water velvet
Cyathea [Sphaeropteris] cooperi (Hook. ex F. Muell.) Domin – Australian tree fern
Platycerium bifurcatum (Cav.) C. Chr. Elkhorn fern, Staghorn fern
Salvinia molesta D. Mitch Salvinia, Water fern, Kariba weed, Africanpayal
Centaurium [Gentiana] spicatum (L.), Fernald spiked centaury
Lygodium palmatum (Bernh.) Sw. Hartford fern, American climbingfern, Creeping fern, Windsor fern

See also The Global Compendium of Weeds: www.hear.org/gcw/pdfs/gcw_intro.pdf

The experience in Hawaii with Salvinia is worth noting: It is an aquatic weed and can be a serious problem. At that time, Hawaii was in the midst of cleaning the weed from a 300 acre freshwater lake, 90% of which was choking with the weed. It has taken many staff-hours, heavy equipment, and lots of herbicide to clear it. So far, about a 1/4 of the lake has been cleared, with much work remains. The correspondent had not seen anything like it during his 30 years working for the Hawaii Department of Agriculture.