Family: Schizaeaceae (Curly-grass Family)
Native range: Old World; L. japonicum ranges from the East Indies, eastern Asia (including Japan), and Australia; L. microphyllum is native to Australia, tropical Asia, and Africa.
Description: Both species are twining vines with black, wiry, threadlike roots. Pinnae (leaflets) are somewhat triangular in outline, especially on L. japonicum, and the pinnules (secondary leaflets) are deeply dissected with ten or more marginal spikes. On L. japonicum, the terminal pinnule is elongated. Fertile pinnules are margined with many spikelets of spore cases.
Ecological threat: Climbing ferns invade a variety of native habitats which include pine flatwoods, cypress swamps, wetland marshes, and mixed hardwood swamps. Climbing ferns form dense populations that can overtop and smother trees, shrubs and, eventually, entire forests. Climbing ferns also form thick mats of plant material on the forest floor, sometimes four feet deep or more, to the total exclusion of native plants. The dense root mats can also alter the flow of water in streams and forested wetlands. The plants adversely alter fire ecology by creating a flame ladder that carries fire high into the canopy of forests, and also allows fire to burn into flooded cypress swamps where it normally would be suppressed. Clumps of burning fern are carried easily by wind and increase fire spotting.
Distribution in Florida: L. japonicum is frequent from north Florida south to the central peninsula; L. microphyllum is frequent in central and southern peninsular Florida.
Background: These ferns were introduced into Florida sometime in the late 1960s for use as a landscape plant and for use in hanging baskets. L. microphyllum is estimated to have infested about 39,000 acres in Florida by 1997. Both species are aggressively invading native habitats in Florida and their further spread is likely.
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