Tuberous sword fern
Native to: the global tropics
Found growing on a roadside in Sumter County, Florida in 1933 (Ward 2000) and in cultivation in Floral City, Florida in 1938 (Ward 2000). It is now established in pine rocklands, flatwoods, marsh edges, and hammocks of conservation areas of south Florida and as far north as Georgia and Alabama. Still available in horticulture, it is sold under various names (e.g., Boston fern, hardy fern, large fern, erect sword fern) and names are often interchanged among the different species. Tuberous sword fern is most often confused with and sold in some stores as the native sword fern. For clarity on this confusion, see the EDIS Document Natural Area Weeds: Distinguishing Native and Non-Native “Boston Ferns” and “Sword Ferns”.
Habit: forb/herb, wood fern
Fronds: both fertile and sterile fronds are pinnate, up to 3 feet in length and 3 inches wide. There are many leaflets, or pinnae, ranging from 40-100 mm (1.5 to 4 inches) on each side of the rachis. Each pinna is oblong to lanceolate with an auricle that overlaps rachis.
Roots: orange/brown to pale brown with linear scales having hair like tips. Stolons are straw colored and produce small underground tubers. The presence of tubers distinguishes it from other wood ferns present in Florida.
Reproduction: numerous sori (spore containing structures) are produced between the leaflet midvein and margin. Dispersal occurs via spores and through the movement of stolons, tubers, and rhizomes.
Distribution in Florida: throughout the state.
Through its aggressive spread, sword fern forms dense stands quickly displacing native vegetation. Because it is a true fern, it reproduces via spores. Thousands of spores can be produced by one plant which are then dispersed by wind and water. Spore production occurs year-round in south Florida.
Do not plant. Clean shoes, equipment, and clothing after managing or visiting infested areas.
Remove existing plantings, before spores are produced if possible. Hand pulling can be used to remove some of the vegetation, but the plants will break off, leaving plant parts in the ground from which regrowth will occur. Be sure to dispose of plants properly.
More research needed.
Herbicides containing glyphosate - a foliar application of a 1.5% solution provides good control. Follow-up applications are necessary to control plants regrowing from rhizomes and tubers. Reach out to your local UF IFAS Extension for further assistance with management recommendations.