Lowland Brittle Fern Cystopteris protrusa

The southern fragile fern is a short, rhizomatous, herbaceous perennial fern in the spleenwort family (Aspleniaceae). The name of the genus comes from the Greek words kystis, meaning “bladder,” and pteris, a fern. The name highlights the indusium, which is inflated when young. The specific epithet, protrusa, refers to the fact that the rhizome extends a short distance (less than 2 inches) beyond the latest frond.

The fern grows well in dappled sun to deep shade. It does best with soil high in organic content, a neutral pH soil and good drainage. It grows 0.5 to 1.5 feet high and wide.

This easy-to-grow fern is an NC native found in the mountains and piedmont regions of the state. Interestingly, it is the only species in the genus that grows on the forest floor rather than on rocks or cliffs. The fronds appear in the spring and have central stems (stipes) that break easily, hence the common name. They often turn brown and begin to disappear by mid-summer. The frond structure is bipinnate-pinnatifid to pinnate-bipinnatid with the leaflets becoming less differentiated toward the tip of the leaf blade. The sori are circular and partially covered by a bladder-shaped indusium. They turn dark brown to black as the spores mature in late spring to mid-summer.

The Southern Fragile Fern can be grown in native and shade gardens and as a border feature. 

Insects, Diseases, and Other Plant Problems:  No serious insect or disease problems.

VIDEO Created by NC State Extension's Homegrown series featuring Mark Weathington, Director of JC Raulston Arboretum.