Java fern

Care at a glance

One fern, many blades

Windelov's lace tips, Trident's forks and Narrow Leaf's slim blades are all selections of the same fern, kept in circulation by nurseries because they hold their shape. Botany reshuffled the genus from Microsorum to Leptochilus, but the plant in shops did not change, and neither did its care.

Plantlets, not problems

Mature leaves grow black bumps along their undersides and edges, and old leaves sometimes brown off while tiny plants sprout from them. That is how java fern reproduces: each plantlet can be pulled off once it has roots and tied down as a new fern. It is easy to mistake for disease, and it never is.

The rhizome stays in open water

Java fern feeds through its rhizome and roots from the water column, not the substrate. Bury the rhizome and it rots; tie or glue it to wood or rock and it slowly walks across the hardscape, leaf by leaf.

Overview

Tie or glue the rhizome to wood or rock and leave it on the surface, since burying the rhizome in substrate rots it and kills the plant. It thrives in low light with no CO2, drawing nutrients straight from the water column, which makes it one of the most forgiving plants in the hobby. Growth is slow, and the most common scare is older leaves developing black spots and brown patches, which is usually normal plantlet production rather than disease, so leave those leaves until the babies are large enough to detach.

In the wild

Native to Southeast Asia, from Malaysia and Thailand through northeastern India and parts of southern China. It grows along streams, waterfalls and riverbanks, attached to rocks, riparian roots and wood. In the wild it lives both fully submersed and emersed, as long as the rhizome and roots stay wet, so it handles seasonal water level changes well.

Good to know

A fern in the family Polypodiaceae, now formally Leptochilus pteropus though still sold everywhere as Microsorum pteropus. It grows from a creeping rhizome rather than a true root system, anchoring with fine brown holdfast roots instead of feeding from substrate. It is highly variable in the wild, which is why so many leaf forms exist, and it reproduces asexually by sprouting adventitious plantlets from leaf tips and margins as well as by spores.

Common questions