Lygodium japonicum aka Japanese Climbing Fern

Lygodium japonicum is also called Japanese climbing fern. This climber lives for more than one year. It grows from the ground and spreads through creeping rhizomes, or underground stems. Kew places its native range in tropical and subtropical Asia, reaching Palau. Other sources list Japan, New Guinea, and Australia as native lands. It climbs through shrubs and trees where forests have regrown. It has also spread into several southern US states.

Sources give heights of 33 feet [10 metres] to 90 feet [27.4 metres]. NC State lists a spread of 15–30 feet [4.6–9.1 metres]. Its long fronds wind around nearby plants for support. Thin, strong stems range from green through orange to black. The green fronds split twice to form smaller leaflets. Fine cuts mark these leaflets, which have hairs beneath them. Fertile leaflets have narrow lobes with parts that make spores. The fern keeps its leaves in tropical climates. Frost can make it lose its leaves.

This fern makes no flowers or fruit. Wind spreads spores from the edges of fertile fronds. Parts of growing fronds can also take root and spread. It grows fast in sun or shade, even deep shade. Sources say to grow it with its roots in shade. Its growth then reaches toward the sun. It prefers moist loam that drains well. Soil should be slightly acid to neutral. Yet it also grows in dry pine habitats. NC State lists USDA hardiness zones 7–13. It resists deer and grows in shade. These traits do not make up for its spread.

People have grown it to screen structures and shade other plants. NC State says not to use it in gardens or landscapes. It can smother trees and form mats on the ground. These mats can block seed growth beneath them. Several southern states list it as invasive. Florida lists it as a noxious weed. Its climbing growth can carry fire into tree crowns. Burning fails to control it, as it grows back fast. Some herbicides have had an effect, but control stays hard. NC State reports no known pests or diseases.

People split its stems to make baskets, hats, and small boxes. Its fibrous roots can serve as a growing medium. Folk medicine uses its leafy parts and spores for chest and urinary complaints. These records show uses, not proof that treatments work or are safe. Useful Tropical Plants lists no known food use. It reports no records of toxicity specific to this species. This lack of records does not mean it is safe.