Old World climbing fern
Native to: native to tropical and subtropical Africa, Asia and Oceania
The first record in Florida was collected from a plant in cultivation at a Delray Beach nursery in 1958 (University of Florida Herbarium record). Subsequently, a collection was made from the wild in Martin County in 1960 (Florida State University Herbarium record), and two additional collections were made from the wild in Martin County in 1965 (University of Florida Herbarium record). By 1978, it was well established. New OWCF populations are found in areas far from existing populations because the fern can reproduce by wind-dispersed spores. Spores are produced year-round in south Florida, and a single fertile leaflet can produce up to 28,600 spores, with each spore capable of starting a new population at a distant location. Area coverage of the fern increased from 27,000 acres in 1993 to 122,787 acres in 2005. There are no more recent estimates of OWCF acreage than 2005. However, mapping efforts continue, and new locations are frequently detected. Today it is one of Florida’s most detrimental and difficult to manage invasive plants.
Habit: a fern with climbing fronds. What looks like a stem is actually a climbing, freely branching, leaf (frond) which may become as much as 100 feet long.
Description: The leafy branches off the main stem are 2-5 inches long. Two types of leaflets present on its climbing leaf. The leaflet with the simple (unlobed) outline is a normal vegetative leaflet. The more convoluted leaflet has sporangia along its margin, which produce spores leading to the development of gametophytes. Gametophytes are separate small plants that produce sexual cells, which unite to form an embryo and ultimately a new climbing fern. This alternating of vegetative and reproductive plants as separate generations is typical of most ferns. The reproductive plants (gametophytes) are usually very small, and rarely seen without considerable detective work. Windborne spores 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.
Distribution in Florida: reported throughout the south and central peninsula and as far north as Duval County on the East Coast.
Climbs into the tree canopy and competes with trees and understory vegetation for light. It can completely engulf Everglade tree islands, pinelands, and cypress swamps, and spreads across open wetland marshes. It can kill mature trees along with their associated epiphytic orchids and bromeliads, and smother understory vegetation, preventing regeneration of the native plant community. As time progresses, a thick mat of old fern material accumulates on the ground, severely altering the habitat. When fire occurs, the fern carries fire into the tree canopy, causing greater damage and transporting fire through wet areas that otherwise present a boundary to the spread of fire.
Since the microscopic spores are easily transported via clothing, wind and possibly water, contamination is a constant threat. If control measures are employed during spore formation and dispersal, then these areas should be treated at a time when workers will not be traveling to other sites in the same day. Take care not to drive equipment through the fern foliage, as this will also help to minimize spore movement. Thoroughly decontaminate clothing, equipment, and vehicles.
Because OWCF distribution continues to expand in Florida, any suspected sightings outside of its current know range should be reported immediately to EDDMapS.
Remove small plants, being sure to get all root material.
More research is needed. Often challenging or not feasible due to the sensitive habitats infested.
From 2005 to 2007, a defoliating moth, Austromusotima camptonozale, was released in southeast Florida but failed to establish. Another species of defoliating moth, Neomusotima conspurcatalis, has established from releases made in 2008 and 2009. Populations are thriving in several areas and have spread to other points beyond the initial releases. The insect has caused considerable localized brownout of OWCF in certain areas. However, the overall impact remains very limited.
Herbicide products that contain the active ingredients glyphosate, triclopyr, and metsulfuron are active against OWCF. Research found that repeated treatment every six months for two consecutive years resulted in a >96% reduction in OWCF cover. This study also found that OWCF recovery was initially from rhizomes at 6 months after initial treatment. However, almost all OWCF recovery at 12 months after initial treatment and beyond was from spore germination. The bottom line is that an aggressive multi-year treatment approach is necessary to effectively control OWCF. More information: Natural Area Weeds: Old World Climbing Fern