Cinnamon Fern

Osmunda cinnamomea, more commonly known as the Cinnamon fern, is a deciduous perennial fern [4]. It looks very similar to the Interrupted, Royal, and Sensitive ferns because of its composition, but using the reproductive fronds you can tell them apart [1]. The Cinnamon fern has cinnamon-colored fiddleheads specially used for reproduction, and that's where it gets its name [1].

Photo of a grouping of Cinnamon Ferns.

Description

Cinnamon ferns have long green fronds that are typically 2-3' in length but can reach up to 6' [5]. The blades of these fronds are pinnate, which means they share a common axis from which the pinna or the leaflets will grow [1]. Leaflets are deeply lobed, come to a point, and are about ten inches in length [1]. This fern likes to grow in groups or clumps in very moist environments [5]. During the spring, spore-bearing fronds will develop on this plant, these are known as "fiddleheads" [5]. These fiddleheads emerge from the base of the fern for reproduction [5]. Fiddleheads on Cinnamon ferns are anywhere from 2-4' long, are very stiff, and have a yellow-greenish color [5]. On the outside of these reproductive fronds, there are small cinnamon-colored balls. These are their sori and sporangium [3].

Anatomical Diagram of a Fern.

Osmunda cinnamomea

Classification	Title
Kingdom	Plantae
Phylum	Filicinophyta
Class	Filicopsida
Order	Filicales
Family	Osmundaceae
Genus	Osmunda
Species	Osmundastrum cinnamomeum

Reproduction

Photo of Cinnamon Fern Fiddlehead.

During the springtime, ferns will produce fertile fronds known as "fiddleheads" [5]. These fiddleheads are covered with sori and have the sole purpose of reproduction [1]. This fern becomes fertile in May and ends its reproductive period in June [4]. Ferns reproduce differently from other plants; they have a sporophytic life cycle [2]. First, the sporangium from a mature adult plant will open and release the egg and hopefully get find male sori to start the germination process [2]. After the first fertilization, the zygote begins to become a gametophyte/Prothallium. Once the Prothallium has matured it will undergo a second fertilization [2]. This second fertilization will mark the beginning of the Cinnamon ferns' journey to maturity and the cycle can begin again [2].

Diagram of a fern's life cycle.

Range and Habitat

Cinnamon ferns are primarily found in the Eastern United States and Canada, although have been found in gulf coast states, like New Mexico [1]. Like all ferns, the Cinnamon fern likes very moist, acidic, and shady soils [1]. This plant typically likes wetland environments such as swamps, marshes, and wet forests [1]. This plant is slow to establish itself, but once it does it is long-lived [5]. If the soil becomes too dry this fern may go dormant until conditions are moist again [5].

Uses

The Cinnamon fern is not used as a food source by any wildlife, but it does have uses. Parts of this fern are used by Warblers and hummingbirds for their nests [1]. Brown Thrashers and Veeries are reported to live in the base of this fern and claim it as their nest [1]. In the past Cinnamon ferns have been used by the Abnaki and Menominee Native Americans for food and medicinal purposes [1]. They used a concoction of root material and rubbed it into affected joints to relieve pain [1].

References

[1] Adirondack Ferns: Cinnamon Fern | Osmundastrum cinnamomeum. (n.d.). . https://wildadirondacks.org/adirondack-ferns-cinnamon-fern-osmundastrum-cinnamomeum.html.

[2] Australian National Botanic Gardens, P. A. (n.d.). Growing ferns from spores - Australian Plant Information. https://www.anbg.gov.au/ferns/fern.spore.prop.html#:~:text=Ferns%20do%20not%20flower%20but,shaped%20plants%20known%20as%20prothalli.

[3] Cinnamon Fern & Interrupted Fern | Mountain Lake Biological Station, U.Va. (n.d.). . https://mlbs.virginia.edu/organism/cinnamon-interrupted-ferns#:~:text=Besides%20sexual%20reproduction%2C%20the%20ferns,cinnamon%20%E2%80%9Cfruiting%20bodies%E2%80%9D).

[4] Lady Bird Johnson Wildflower Center - The University of Texas at Austin. (n.d.). . https://www.wildflower.org/plants/result.php?id_plant=OSCI.

[5] Osmundastrum cinnamomeum (Cinnamon Fern) | North Carolina Extension Gardener Plant Toolbox. (n.d.). . https://plants.ces.ncsu.edu/plants/osmundastrum-cinnamomeum/.