Cinnamon Fern
Osmunda cinnamomea
Osmundaceae
John and George used today for curriculum development and missed getting into the great blue yonder, but George’s Native Plants class Thursday seized the day in Jonathan Dickinson State Park to savor a dairy display of Milkworts, Elliott’s Milkpeas, and Butterworts mixed with the best crop of Grasspink Orchids (Calopogon species) I’ve ever seen there. High in the old dead pine tree near the Loxahatchee River a young osprey pondered humans from a safe perch.
One of the standout species in Jonathan Dickinson Park is Cinnamon Fern, an old friend from earlier times in Michigan and Massachusetts. Partly because of their wind-blown spores, ferns often have broad distributions, in this case from the Arctic Circle across the Equator to southern South America, and from the U.K. (cultivated?) through Siberia to Japan. Fairly impressive! And we wonder why it is often impossible to specify if a fern is “native” to a given locale.
This is one pretty fern, popular in the garden as in the wild. The fronds stand about 2-3 feet tall in a tuft resembling a badminton birdie, and the cinnamon-colored spores form on giant vertical cinnamon sticks. Unsure of the identification? Peep where the leaflets join the main leaf stalk; there’s a telltale tuft of tomentum.
Now a quick lesson on seed plants and ferns. Most land plants protect their most tender reproductive phase within a seed. But ferns have no seeds. Instead, their spores germinate, not directly into a new fern, but rather into a tiny tender plant the size of your pinkie fingernail or smaller, called a gametophyte (gam-EET-oh-fight). The gametophyte makes the eggs and sperms required to regenerate the mature fern plant we all recognize. The gametophyte is tiny, moisture-dependent, sun-averse, and oh-so-exposed and fragile. But hold on—not that tender and fragile. Cinnamon Fern puts the fight in gameto-fight.
Ferns compete like beasts in the jungle. And the best way to smite your ferny foe is to strike when it is young and tender. In short, go for the gametophyte! It’s bloody combat down there in mud. Recent research in the American Fern Journal showed Cinnamon Fern gametophytes get along dandy with other Cinnamon Fern youngsters, but if you mix them with gametophytes of a different species, somebody gets hurt. When you combine Cinnamon Fern gametophytes with those of another species, the competitor suffers a dramatic setback, even if all you do is water the competitor with water where Cinnamon Fern babies have been. Poison! But don’t start a fight if you can’t take a bloody nose—turns out the other species returns fire, giving our friend Cinnamon Fern a setback of its own.
Plant your spores and place your bets!




Jen Foglia
April 26, 2014 at 12:02 am
I want to know what happens! Can someone give more information about it? Im very curious.
George Rogers
April 26, 2014 at 7:26 am
Jen, Ther is an article reporting this in the American Fern Journal.. Not that much detail there though. I don’t think it is available on-line, but try this: Google “Osmunda cinnamomea allelopathy” or “Osmunda gametophyte allelopathy” and you will find some info…
Jen Foglia
April 27, 2014 at 11:10 am
Thank you! Ill check it out!
SmallHouseBigGarden
April 27, 2014 at 10:10 am
absolutely EXCELLENT teaching in this post! Thank you for making it so entertaining I’ll never forget these cinnamon fern.
George Rogers
April 27, 2014 at 11:07 am
And Cinnamon Fern is a great garden plant
George Rogers
April 27, 2014 at 11:17 am
I have a copy of the Am. Fern J. article, and glad to share it of course, but there’s really nothing much more in it—basically how they made the determination, not more interesting biological insights or details.
Jen Foglia
April 27, 2014 at 11:25 am
I saw an interesting show on bladderworts, they’re also carnivorous.
George Rogers
April 27, 2014 at 2:50 pm
Wish I had caught it
Mary Hart
April 29, 2014 at 5:10 am
UK boasts a multitude of ferns including an abundance of Regal fern – even my tiny garden has Ferns – i love them.
George Rogers
April 29, 2014 at 10:08 am
They’re easy to love. Probably better suited to cultivation in the U.K. than here, although even in S. Florida there are examples of terrific Royal Ferns in moist shaded gardens.