Climbing Maidenhair (Invasive Exotic Plants of North Carolina)

Climbing Maidenhair

Lygodium microphyllum

Summary ⁶

Lygodium microphyllum (commonly known as, variously, climbing maidenhair fern,Old World climbing fern,small-leaf climbing fern, or snake fern) is a climbing fern originating in tropical Africa, South East Asia, Melanesia and Australia. It is an invasive weed in the US States of Florida and Alabama where it invades open forest and wetland areas. The type specimen was collected in the vicinity of Nabúa, on the Island of Luzon in the Philippines by Luis Née.

Distribution ⁷

More info for the terms: fern, ferns, nonnative species

Japanese climbing fern is native from India, east through southeastern Asia and China to Japan and Korea, and south to eastern Australia (Singh and Panigrahi 1984 as cited in [5]). North American establishment was first recorded in the early 1900s in Georgia (Clute 1903 as cited in [25]). Japanese climbing fern is now introduced throughout the southeastern United States from Texas and Arkansas to North Carolina, and also in Puerto Rico (Proctor 1989, Nauman 1993 as cited in [5]). It is considered a "problem weed" from central Florida west across the southern half of the Gulf states [28].

Old World climbing fern is native to tropical and subtropical areas of Africa, southeastern Asia, northern and eastern Australia, and the Pacific islands (reviewed by [5,24]). In North America it is found in southern and central Florida [21,44]. Large parts of the Caribbean, Central and South America, and perhaps coastal areas of southern Louisiana and Texas may also be vulnerable to Old World climbing fern invasion [10,23,25]. Old World climbing fern was first collected from the wild in southern Florida in 1960 [15]. As of 2005, Florida Plant Atlas [42] showed Old World climbing fern distribution in southern Florida from coast to coast and as far north as Hillsborough and Brevard counties. Ecological/climate modeling indicates Old World climbing fern could become established throughout most of southern Florida, with northern distribution extending furthest along the coasts [10].

Ferriter [5] reviewed the history of climbing fern invasion in the southeastern U.S.

The Flora of North America provides distribution maps of climbing ferns.

The following biogeographic classification systems demonstrate where Japanese climbing fern (labeled with the abbreviation J) and Old World climbing fern (O) could potentially be found based on floras and other literature, herbarium samples, and confirmed observations. Precise distribution information is unavailable. In general, predicting distribution of nonnative species in North America is difficult due to gaps in understanding of their biological and ecological characteristics, and because they may still be expanding their range. Therefore, these lists are speculative and may be imprecise.

Impacts and control ⁸

More info for the terms: cover, fern, ferns, fire management, fronds, interference, natural, shrub, shrubs, top-kill, tree

Impacts: Although there are few studies documenting the impacts of climbing ferns on native plants and ecosystems in the southeastern U.S., their invasion is likely to have deleterious effects. Nauman and Austin [21] reported that climbing ferns are established, persistent, and spreading in Florida, Japanese climbing fern in the north and Old World climbing fern in the south. A review by Ferriter [5] suggested that climbing ferns don't require "human disturbance in order to spread and become established."

Most accounts of impacts associated with climbing fern invasion (e.g. reviews by [1,15,16,21,25,41]) describe interference with native plants due to a prodigious growth habit. Climbing ferns can produce thick mats along the ground, severely reducing native ground cover. A review by Wood [41]) indicated that Old World climbing fern can form mats up to 4 feet (1.2 m) thick. They also climb into forest canopies, shading trees and shrubs that it covers, weakening or killing them, their associated epiphytic orchids and bromeliads, and understory plants.

Japanese climbing fern Old World climbing fern Â©Barry A. Rice/The Nature Conservancy Â©Mandy Tu/The Nature Conservancy

Of particular concern may be climbing fern impacts on native vegetation within many of the region's high-quality natural areas. A review by Pemberton and others [23] indicated that, as of 2004, Old World climbing fern was rapidly spreading in southern Florida, including in Everglades National Park. Volin and other [38] expressed concern that efforts to restore Everglades hydrology to approximate a "pre-drainage environment," while perhaps reducing establishment and spread of many important nonnative plant invaders, may "improve the ecological conditions for Old World climbing fern." Lott and others [16] reported that Old World climbing fern "has been observed overtopping tree canopies among tree islands in the Arthur R. Marshall Loxahatchee National Wildlife Refuge" [16]. Volin and others [38] recorded an average of 14 Old World climbing fern infestations (defined as contiguous growth that had climbed above the shrub layer on 1 or more trees) per km2 along transects in the Big Cypress National Preserve and Big Cypress Seminole Indian Reservation. The most heavily infested transect contained 58 infestations per km 2.

Climbing fern invasion may also impact rare and threatened taxa. Reviews by Ferriter [5] and Langeland [15] indicate that climbing fern invasion in Florida threatens the rare plant ray fern (Actinostachys pennula), as well as the endangered Georgia bully (Sideroxylon thornei), common dutchmanspipe (Aristolochia tomentosa), and branched tearthumb (Polygonum meisnerianum).

Control: Removing dead material following climbing fern control activities may be desirable to reduce fuels and to promote native plant recovery. On-site disposal of dead climbing fern material, such as by burning, can reduce spore dispersal (reviewed by [5]).

Ferriter [5] provides an extensive review of climbing fern management in Florida, available online through Florida Exotic Pest Plant Council.

Prevention: Frequent monitoring and immediate removal of newly established climbing fern populations may be the best strategy for mitigating their spread, especially since spore production can be prolific and spores may be dispersed over vast distances [5].

Integrated management: No information is available on this topic.

Physical/mechanical: Repeated pulling and/or cutting can control small climbing fern infestations (reviewed by [28]). Cutting kills fronds above the cut site, but fronds can regrow from below the cut site and after pulling (reviewed by [5]).

Fire: See the Fire Management Considerations section of this summary.

Biological: Pemberton [24] and Pemberton and others [23] reviewed the developmental status (as of 2004) of biological control of climbing ferns in North America. In February 2005, more than 100 individuals of Austromusotima camptonozale, an Australian moth and the first biological control agent approved for use against Old World climbing fern in the United States, were released at the Jonathon Dickinson State Park, southeastern Florida. Larvae of A. camptonozale feed on Old World climbing fern leaves [6].

Chemical: Several sources indicate herbicides may be an effective tool for controlling invasive climbing ferns. A review by Langeland [15] suggests the most common climbing fern control method, as of 2004, has been application of glyphosate and metsulfuron herbicides, either individually or in combination. When plants have grown into the canopy, stems may be cut and herbicide applied to the rooted portion of the plant [15]. Roberts [30] indicated foliar spraying of glyphosate can control Old World climbing fern, but few data and no analysis were provided. Descriptive results from several "demonstration trials" in southeastern Florida suggest that glyphosate, triclopyr, and 2,4-D can be used to at least top-kill Old World climbing fern, and that triclopyr ester (vs. triclopyr amine) may be "translocated" within the plant following application [36]. According to Randall [28], managers at Florida Caverns State Park have treated large Japanese climbing fern infestations by pulling the plants down from the trees and spraying their foliage with triclopyr. A review by Ferriter [5], citing unpublished data, indicated that glyphosate was effective for controlling Japanese climbing fern, although some follow-up spot treatments were necessary. Triclopyr treatments, while initially providing greatest observed Japanese climbing fern mortality, were ineffective in the long term due to extensive regrowth.

Other authors have indicated that herbicide use for climbing fern control may be problematic. A review by Stanturf and others [34] suggested that Japanese climbing fern "cannot be controlled by any available herbicide." Old World climbing fern can apparently "regrow after spraying" with herbicides (reviewed by [41]), although further details describing the biology of this phenomenon are lacking. Pemberton and Ferriter [25] suggested that chemical control of Old World climbing fern (and presumably also Japanese climbing fern) will be difficult without damaging associated vegetation.

Cultural: No information is available on this topic.