Osmunda claytoniana

Interrupted Fern is a native, herbaceous perennial, in the Royal-fern family (Osmundaceae) found in central and eastern parts of Canada and the United States in upland forests where the climate is moist to rather dry. The genus name honors Osmundus or Asmund, ca. 1025, a Scandinavian writer of runes who is said to have helped prepare the way for the Swedish acceptance of Christianity. The species epithet honors John Clayton (1686–1773), who came to Virginia from England in 1705.

This plant is wiry and clump-forming and will grow 2 to 4 feet high in a spreading vase form 2 to 4 feet wide. It is short-lived and has the habit of dying off in the center of the clump but continuing to grow around the outside edge. Interrupted Fern is one of the first ferns to grow in the spring and spreads slowly by horizontal rhizomes. It has fertile leaflets that develop in the middle of fronds. When the fertile leaflets appear in spring, their unusual appearance can make the plant look like it is afflicted with a disease. These fertile leaflets wither away, leaving an interruption between the upper and lower leaflets on the leaf, thus the common name.  

Interrupted Fern is easy to grow and prefers moist, average to humus-rich, acidic soil, in sun or shade. However, it will adapt and grow in dry, stony soil. It can be grown as a companion plant with hostas in shaded woodlands or wild gardens or along ponds or streams. It also makes an interesting accent for a shaded border. 

Diseases, Insect Pests, and Other Plant Problems: No significant problems. This plant is seldom damaged by deer or rabbits.

VIDEO Created by Elisabeth Meyer for "Annuals, Perennials, Vines, and Groundcovers" a plant identification course offered in partnership with Longwood Gardens.