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Osmundastrum cinnamomeum

Cinnamon fern

Plant Details

Common Name: Cinnamon fern
Family: Osmundaceae
Mature Height: 2 - 5'
Sun Requirement: Part shade to shade, Shade
Moisture Requirement: Medium - moist, Moist
Flower Color: None
Bloom Time: None

Osmundastrum cinnamomeum Cinnamon fern
Osmundastrum cinnamomeum Cinnamon fern
Osmundastrum cinnamomeum Cinnamon fern
Osmundastrum cinnamomeum Cinnamon fern
Osmundastrum cinnamomeum Cinnamon fern

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Etymology

The origin of Osmundastrum is unclear. The most popular theory is that it was originally derived from the name Osmunder – the Saxon name for the Norse god Thor, who (according to legend) hid his family from danger in a clump of these ferns. 

Cinnamomeum is latin for cinnamon-colored; in this species it is in reference to the color of the hairs on the young petioles, rachis, and pinnae.

Native Habitat

Cinnamon ferns prefer wet acidic soil and shady to partially shady sites. Although this plant occasionally occurs in non-wetlands, cinnamon ferns are more likely to be found on poorly-drained sites in swamps, marshes, and wet forests.

Garden Uses

Excellent low-maintenance selection for shady wet areas along ponds, streams, water gardens or in bogs. Also grows well in shaded borders or woodland gardens. Resistant to garden challenges like deer, heavy shade, and wet soil.

Overview

The fronds of cinnamon fern grow in 2 to 3 foot tall clumps that rise from a shallow, black rootstock. Fertile fronds appear first as silvery, furry fiddleheads, then unfurl into bright green, lacy, broad fronds in early spring, and ultimately become large, erect, pinnately-compound fronds (2 to 4 feet long) which remain attractive throughout the summer and turn a lovely yellow or copper color in autumn. Separate spore-bearing, stiff, fertile fronds appear in the center of the clump in early spring and quickly turn brown. The sterile green fronds bend outwards forming a vase-shaped circle around the fertile "cinnamon" fronds. The contrasting visual of fertile and infertile fronds can make for dramatic accents in a landscape. The common name of this plant is in reference to the cinnamon colored fibers found near the frond bases, and for the brown fertile fronds that grow in the center of the clump. Though it typically grows 2 to 3 feet tall, cinnamon ferns can reach 5 feet in height in settings where there is constant moisture.

Leaves and Stems

The leaves of this fern consist of circular clusters of arching fronds, sometimes reaching 5 feet in length but are typically 2 to 3 feet. Sterile fronds are lanceolate and pinnate with dense rusty hairs beneath the base of each pinna (leaflet). The pinnae are narrow, lance-shaped, pointed, deeply cut and nearly opposite. Fall leaf display ranges from yellow/gold to brown/copper.

Wildlife Associates

Ruffed Grouse reportedly use the fiddleheads as a food source, and the downy wool from these ferns may be used as a nest lining by Yellow Warblers and hummingbirds. Brown Thrashers and Veeries are said to nest in the central parts of the fern’s clump.

Propagation

Propagate by fresh, green spores in mid-summer or by rhizome division. In older clumps division can be challenging.

Ethnobotanical Uses

Cinnamon ferns were used by a number of native American tribes for medicinal purposes. A decoction of the root was reportedly rubbed into affected joints to treat rheumatism. The plant was also used as a remedy for chills, headache, joint pain, and colds. In recent history, the fern’s bristly root crown has been harvested to create “osmunda fiber”, which was once widely used as a potting medium for orchids.

Garden Location

West Woods (see garden map)

Anecdotal Information

With age, the rhizome will produce separate clumps of fiddle heads around the perimeter root mass.

Sources

Lady Bird Johnson Wildflower Center

Missouri Botanical Garden

North Carolina Extension Gardener Plant Toolbox

Wild Adirondacks

Plant Profile by Rachel Emus