Schizaeaceae, the Curly-Grass Fern Family
This fern is unusual with its twining habit and with fronds growing to about 100 feet long. The rachis is slender and wiry with petiolelike stalks that attach to each pinnule (leaflet) and remain as a stub when the leaflet falls off. The sterile pinnae are roughly triangular or somewhat heart-shaped, once compound and not lobed, but the fertile pinnae have a fringe along the leaflet margins created by rolled leaf tissue that covers the sporangia. Both fertile and sterile pinnae are borne on the same fronds.
Old World climbing fern is native through much of the tropics, including tropical Africa, Asia, Australia and Pacific islands.
In Florida, this fern is found throughout most of the peninsula, and a separate population has been documented in Duval County. It is found growing in wet areas, such as flatwoods, moist hammocks, swamps and floodplain forests, as well as weedy areas including abandoned fields, drainage ditches and other disturbed places.
The invasive Japanese climbing fern (L. japonicum) is becoming a serious pest in North Florida, but it has been collected throughout the state. The very rare native Hartford fern (Lygodium palmatum) has distinctive palmately lobed pinnae, but it is probably no longer surviving in Florida.
Windborne spores of this fern remain viable for up to four years after they are released. The plant grows new fronds and produces spores throughout the year. The rhizomes form dense, wiry, brown mats that can increase rapidly.
This species has escaped from cultivation and is now classified as a noxious weed in Florida and Alabama and is listed as a Category I invasive by the Florida Exotic Pest Plant Council. Like its invasive relative, Japanese climbing fern, it covers native vegetation, including trees, and can serve as a ladder for fire to climb into the forest canopy. This fern is also an agricultural weed in parts of Asia.