Science for Everyone

The Ferns of Hurricane Island

Post by Chloe Tremper, Science and Education Intern

If you find yourself hiking around Hurricane Island's trail system and come across a fern, take a closer look! Can you identify it? Here are different types of ferns we have found this summer. It may help to check out this helpful diagram showing fern anatomy before reading below.

Mountain Wood Fern Dryopteris campyloptera (Kunze) Clarkson.

 Sori of the Mountain Wood Fern

Sori of the Mountain Wood Fern

 Mountain Wood Fern

Mountain Wood Fern

Mountain wood fern is one of, if not the most abundant fern species on Hurricane Island as it can be seen on nearly every part of the island. These ferns inhabit cool forests throughout New England, though typically are only found on higher elevations in more southern states, hence the name “mountain” wood fern.  Its thrice-pinnate leaf blade, pale green kidney-shaped sori (the little dots on the underside of the main fern blade), brown scales on the leaf stalk, and the veins, which do not reach the edge of the leaf blade, help easily identify this species. Fun Fern Fact: Native Americans used a tea of the leaves to treat stomachaches and used the rhizomes for food.

Rock Polypody Polypodium virginianum L.

 Rock Polypody

Rock Polypody

Rock polypody is another common fern on Hurricane, however you have to know where to look.  Rock polypody often grows directly on rock or on thin soil over rocky cliffs and boulders. We’ve found it growing all over many of the granite rock outcrops within the shade of the spruces and firs here on the island. The blade of rock polypody is once-pinnate and lobed with large, circular sori that tend to be brown in color.  If you look closely at the blade of rock polypody, it almost looks like the pinna are all connected and smoothly zig-zagging back and forth. Fun Fern Fact: It was widely used by Native Americans as a medicinal herb to treat stomachaches, colds, coughs, and other ailments.  

 

Cinnamon Fern Osmundastrum cinnamomeum (L.) C. Presl

 Cinnamon Fern

Cinnamon Fern

Cinnamon fern is abundant along trails mostly on the northern half of Hurricane Island, and these ferns are typically found along water edges and within forests.  Cinnamon fern is a large fern that grows in rounded clumps with fertile fronds emerging from the center.  Unlike mountain wood fern and rock polypody, which have spores on the undersides of their pinna, the spores of cinnamon fern are all found within modified leaflets on individual fertile fronds which look very different from the sterile fronds.  The sterile fronds of cinnamon fern are twice-pinnate and can grow to be over three feet in length and the fertile fronds are erect with cinnamon colored sporangia covering the top of the stalk. Fern Fun Fact: Cinnamon fern fiddleheads are mildly toxic and are often mistaken for ostrich fern fiddleheads, which are commonly collected for food in the spring. Careful what you harvest!

 

Sensitive Fern Onoclea sensibilis L.

 Sensitive Fern

Sensitive Fern

Sensitive fern is fairly abundant on Hurricane Island, especially in poorly drained areas open areas as sensitive ferns are indicators of wet sites and are one of a few ferns that are sun-tolerant.  The blade is once-pinnate with slightly lobed margins on the pinna and a light yellow-green color.  Like cinnamon fern, sensitive ferns have fertile fronds that look like rows of black capsules along the top of an erect stalk growing along with the sterile fronds. Fern Fun Fact:  Sensitive fern received its name because the sterile fronds are very susceptible, or sensitive, to frost damage.

 

Interrupted Fern Osmunda claytoniana L.

 Interrupted Fern

Interrupted Fern

Interrupted fern is a very common fern found throughout New England, however we have only found it one location on Hurricane Island so it’s a rare one for us.  They are generally found in forests and along water edges.  The leaf blade is twice-pinnate and many fronds have distinct interruptions at the center of the frond caused by fertile pinnae. The fertile pinnae are generally chestnut-brown to black in color and close to the stalk.  Fern Fun Fact: Interrupted fern has the oldest known fossil record of any living fern in the world, it's been around for 200 million years!

 

Royal Fern Osmunda regalis L.

 Royal Fern

Royal Fern

Royal fern is a species found commonly around the world, however we’ve only found it in one location on Hurricane so it gets treated like royalty here! Royal ferns are often found by water and within forests.  The leaf blades of the sterile fronds are twice pinnate with a gap between each pinna.  The fertile fronds rise above the sterile fronds and are somewhat crown shaped, thus the name royal fern. Fern Fun Fact: Royal fern is the largest fern found in North America and the young fiddleheads are edible.

Whew! That's all the ferns we've found for now, but stay tuned, and see if you can find any of these ferns growing around your own home or neighborhood! I recommend A Field Guide to Ferns and Their Related Families: Northeastern and Central North America (A Peterson field guide) if you are looking to become a fern expert :) Happy fern finding!

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