The royal fern wears a “crown” of spores.
Photo: Kevin McKeon
Ferns Bring Ancient Beauty to Our Trailsides
By Kevin McKeon, Maine Master Naturalist
Fossil records show that ferns began their life on Earth about 380 million years ago, but recent scientific evidence indicate they’re probably over 430 million years old, making ferns one of the oldest group of plants on Earth — almost twice as old as the dinosaurs. As Earth was cooling from its fiery-hot landscape, algae climbed out of the waters, grew roots, and began locking up a lot of Earth’s carbon. As carbon was sequestered from the atmosphere, Earth cooled enough to allow large leaves to grow without burning: Thus, the birth of land plants, of which ferns were early, prolific adapters.
These plants, mostly ferns, began growing and dying — profusely and unrestrained, without competition and no animals to eat them — among the anoxic swamps of the day for millions of years. The massive accumulating layers of dead tissue, under heat and pressure caused by its own weight, formed the basis of most of our current coal, oil, and gas deposits. So, we’re driving along on plant-powered vehicles, on roads made from plants, to our plant-heated and cooled houses!
An eruption of fern diversity about 70 million years ago resulted in modern ferns’ ancestors displacing the ancients — some of which were tree-sized. Even today, the Norfolk Tree Fern, of that island off the eastern coast of Australia, grows to 65 feet.
An earlier column talked a bit about fern reproduction, with a picture of a fern’s spore-holding sori. And we visited some evergreen ferns that are identifiable during our winter walks. As with most living things, ferns are classified by their species-specific reproductive organs. Ferns don’t have seeds but use spores for reproduction, and some of Sanford’s ferns have spores that are formed on specialized fronds (leaves) that look like stems. Their common names reflect these stems: the ostrich, cinnamon, interrupted, royal, and sensitive ferns. These are called dimorphic ferns; their spore-producing fronds do not photosynthesize like their other fronds do. Ferns that have fronds that both produce spores and photosynthesize are monomorphic ferns.
The Interrupted Fern’s spore-holding sori “interrupts” the stem (stipe) on some of the fern’s fronds. The royal fern holds its sori above the plant in a flower-like arrangement — a “crown” above the bushy plant. Three others — the ostrich, cinnamon, and sensitive ferns — have spike-like fertile fronds that stand alone and apart from the other fronds.
So, as summer enters our Sanford landscapes, trail walks become more enjoyable with the knowledge that these ferns continue to show their ancient beauty during our early summer jaunts along our beautiful trails, held and maintained by the city, our local Mousam Way and Three Rivers land trusts, and some generous landowners.
Fern reproduction and interrupted fern photo: https://sanfordspringvalenews.com/out-in-the-woods-45/
Evergreen ferns: https://sanfordspringvalenews.com/out-in-the-woods-63/
Editor’s note: Did you see something unusual last time you were out in the woods? Were you puzzled or surprised by something you saw? Ask our “Out in the Woods” columnist Kevin McKeon. He’ll be happy to investigate and try to answer your questions. Email him directly at: kpm@metrocast.net
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