Lygodium microphyllum

Name and classification

Lygodium microphyllum (Cav.) R. Br.
(=Lygodium scandens (L.) Sw., Ugena microphylla Cav.)
Family Lygodiaceae

Common names

Old World climbing fern

Disseminule

spores, rhizomes

Description

A large fern with dark brown, wiry rhizomes and climbing, twining fronds of indeterminate growth, to 30 m long; main rachis (leaf stalk above petiole) wiry, stemlike. Leafy branches off of main rachis (the pinnae) once compound, oblong in overall outline, 5–12 cm long. Leaflets (pinnules) stalked, triangular-lanceolate to oblong-lanceolate, truncate to shallowly cordate or somewhat auriculate proximally, usually unlobed, margins entire, apex rounded-acute to obtuse, pinnules articulate (leaving wiry stalks when detached); leaf-blade usually glabrous abaxially. Fertile pinnae similar, fringed with tiny lobes of enrolled blade tissue covering the sporangia along the leaf margin. Spores produce gametophytes with both male and female organs.

Identification considerations

In Florida, this species may be confused with another invasive fern, Lygodium japonicum , whose pinnae are often twice compound and whose sterile leaflets are lobate rather than oblong-lanceolate with margins toothed instead of entire. Lygodium microphyllum is distinguished from L. flexuosum and L. japonicum by having pinnule stalks of similar length along pinnae and pinnules articulated at base and deciduous.

Similar species

Lygodium flexuosum (L.) Sw.

Lygodium japonicum (Thunb. ex. Murr.) Sw. (non-FNW)

Distribution

Native range is large, including much of the moist Old World tropics and subtropics in Africa, Asia, Australia, and Oceania.

In the New World, this fern is naturalized in Jamaica, Guyana, and southern Florida.

Habitat

Capable of growing in wet soils and even in standing water, under light conditions ranging from shade to full sun. Spores require moist conditions to germinate. Invaded habitats include forests, swamps, glades, hammocks, wet grasslands and disturbed areas.

General information

Lygodium microphyllum is a fast-growing, long-lived perennial vine that can overgrow trees and overrun entire plant communities. It is a fire hazard because the dry dead fronds are flammable and carry fires into the tree canopies. Reproduction is both vegetative and sexual, with wind-borne spores traveling long distances and remaining viable for up to two years.

You tube video discussing Lygodium microphyllum populations in Florida.

sterile leaflets (top side, left) and fertile leaflets (underside); photo: Peggy Greb, USDA ARS, Bugwood.org

sterile leaflets (top side, left) and fertile leaflets (underside); photo: Peggy Greb, USDA ARS, Bugwood.org

fertile leaflet, detail; photo: © Amy Ferriter, State of Idaho, Bugwood.org

fertile leaflet, detail; photo: © Amy Ferriter, State of Idaho, Bugwood.org

fern overtaking cypress trees in southern Florida; photo: Peggy Greb, USDA ARS, Bugwood.org

fern overtaking cypress trees in southern Florida; photo: Peggy Greb, USDA ARS, Bugwood.org