Native to the eastern United States and Eurasia, where it is found in sunny wetland areas, marsh fern is a perennial with upright narrow fronds and deciduous light-green leaves. It spreads by rhizomes in the soil, producing dense colonies of leaves up to 2 ½ feet tall as it develops.  Unlike most ferns, it prefers full sun to light shade and grows best in wet to moist surroundings and sandy acid soil. The caterpillars of the marsh fern moth (Fagitana littera) feed on the leaves of this fern—it is the only known host plant of this uncommon moth.