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 developed in partnership with Longwood Gardens.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Dappled Sunlight (Shade through upper canopy all day) | Deep shade (Less than 2 hours to no direct sunlight) | Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand
Soil pH
Acid (<6.0)
Soil drainage
Frequent Standing Water | Moist | Occasionally Wet
Available space
12 inches-3 feet; 3 feet-6 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 2 ft. 0 in. - 4 ft. 0 in. | Width: 2 ft. 0 in. - 4 ft. 0 in.
A rosette of ascending leaves about 2 to 4 feet tall. Each blade is elliptic-oblong in shape, its structure is pinnate-pinnatifid, and consists of 20 or more pairs of leaflets. The leaflets are longest toward the middle of each leaf (if they are sterile), becoming smaller toward both the top and the bottom. The pinnatifid leaflets are deeply lobed and narrowly lanceolate. There are 10 or more pairs of lobes per leaflet; that become gradually smaller toward the tip of each leaflet. The lobes are oblong and smooth along their margins; their tips are well-rounded. The upper surface of the leaves is medium green and glabrous, while the lower surface is pale green. The central stalk of each leaf is light green and terete. The petioles are mostly terete and lack scales. During the spring, rachis, petiole, and underside of fertile leaves are covered with white- or brown-woolly hairs. At this time, fertile leaves also have 2-7 pairs of leaflets toward the middle that are densely covered with spores and somewhat constricted or contorted in appearance. The tiny spores are released through narrow openings during the spring or summer. Infertile leaves leaflets have a normal appearance.
Flower detail
No flowers.
Fruit detail
No fruits. This plants reproduces by means of spores.
Stem color
Brown/Copper
Wildlife & Ecology
Native status
Native
Origin
Eastern Canada and the United States
Distribution
Netherlands
Wildlife value
It provides shelter for small mammals.
Attracts
Small Mammals; Songbirds
Food & Medicine
Uses (ethnobotany)
The heavy rhizomes are the source for Osmunda fiber used in the potting of orchids.