Old World climbing fern: Lygodium microphyllum
The correct name of Old World climbing fern is L. microphyllum,
but the species is occasionally referred to as Lygodium scandens.
As many as 40 species have been placed in the genus Lygodium, but a
recent revision has reduced this number to 26. Lygodium japonicum,
another invasive species in the southeastern United States, has
leaflets that are more dissected and lobed than those of Lygodium
Look for first
- tangle of wiry, twining fronds
- fern-type leaflets
- sporangia under curled leaflet margins
||Leaves: Twining fronds of indeterminate growth to 30 m (90 ft.)
long. Leafy branches off main rachis (constituting the pinnae) once
compound, oblong in overall outline, 5-12 cm (2-5 in.) long.
Leaflets (pinnules) usually unlobed, stalked, articulate (leaving
wiry stalks when detached); leaf-blade tissue usually glabrous
below; fertile leaflets of similar size, fringed with tiny lobes of
enrolled leaf tissue covering the sporangia along the leaf
||Stems: Fern with dark brown, wiry rhizomes forming layered mats
or canopies over existing vegetation.
||Flowers: None. Ferns are a spore-releasing class of vascular
||Spores: Many thousands of tiny spores released per plant and
carried by wind, dust, animals, clothes, and equipment.
Old World climbing fern is an aggressive
nonnative invasive fern of moist habitats in South Florida. This
rapidly spreading fern invades new areas without the need of
habitat disturbance and often completely dominates native
vegetation by forming a dense canopy. The fern, first found to be
established in 1965 in Martin County, now infests more than 200,000
acres in South Florida.
Native to Africa to Southeast Asia, South Pacific islands, and
Australia. In Florida, most common in South Florida but spreading
into Central Florida.
Although primarily a weed of public
conservation areas, Old World climbing fern infests residential
landscapes, horticultural nurseries, rangelands and other managed
lands near infested natural vegetation. The fern's ability to
grow up and over trees and shrubs and to form dense horizontal
allows it to cover whole communities of plants reducing native
plant diversity. Old World climbing fern can grow in bald cypress
stands, pine flatwoods, wet prairies, saw grass marshes, mangrove
communities and Everglades tree islands. Some Everglades tree
islands are so completely blanketed by the fern that it is not
possible to see trees and other vegetation beneath the fern canopy.
The fern poses management problems for both wildfires and
prescribed burns because it can serve as a fire ladder that carries
fire into the tree canopy that kills native trees. Also, portions
of burning fern can frequently break free and spread fire to
surrounding areas. Scientists' estimate that, left unchecked,
Old World climbing fern could infest more than 2 million acres in
South Florida by 2014.
Why the Old World climbing fern must be managed
- Highly invasive in natural areas.
- Severe threat to Everglades tree island communities
- A canopy producer that smothers native trees and shrubs.
- Can serve as a fire ladder that carries fire into native tree
canopies that normally wouldn't burn.
- The fern is rapidly spreading in South Florida's public
climbing fern (Lygodium microphyllum)
Image Credit: Center for Aquatic and Invasive Plants, University of Florida