“Outdoors” people, even those that don’t consider themselves naturalists, can identify trees, at the least common species. And the common wildflowers. But, when it comes to ferns, well, ferns tend to look alike. Sort of lacy and delicate and . . . green.
That is unfortunate, say fern lovers and fern experts.
Ferns are a big part of our northeast woodlands, growing in almost every kind of soil, from dry to very wet and even on rocks. And they are fascinating plants. Tough, with ancient roots, a quirky life cycle and some impressive chemical defenses.
Lynn Levine, a consulting forester in Vermont and the author of the new book identifying Ferns the Easy Way: A Pocket Guide to Common Ferns of the Northeast ($10.95 from Heartwood Press or online), said her fascination with ferns began when she was doing forest inventories, cataloging the tree species, flowers, birds and mammals on a woodlot.
Maidenhair fern is striking, with its lacy foliage. And she noticed that where it grew, there were lots of other wildflowers, and the trees tended to be taller. “It’s generally a calcium-rich site, the geology, with a little bit more nutrients. Ferns like it there and trees grow well there too.”
When she looked into identifying different species of ferns, she didn’t find an easy-to-use guide. So she decided to write one. It was a five-year project. The result is a 74-page pocket guide that can get anyone identifying ferns inside of 25 minutes, she said.
“Ferns are generally very confusing,” she said. It wasn’t until the 1800s, for instance, that botanists nailed down the fact that ferns reproduced using spores. Perhaps the first use of the word spores in the botanical literature in reference to ferns was in 1836.
There are some 12,000 species of fern worldwide. And they are a very old lineage — 150 million years old before the dinosaurs even appeared. They predate flowering plants by some 200 million years.
Michael Sundue, an expert on fern evolution at the University of Vermont’s Department of Plant Biology and the curator of its Pringle Herbarium, points out that most of today’s fern species are not the same as the ones that existed hundreds of millions of years ago, just as modern humans aren’t the same as our ancient ancestors. But, they are no less fascinating, he said.
Ferns make up some 6 to 10 percent of vascular plant diversity throughout the world, with the tropics sporting the greatest diversity, Sundue said. Though it’s the tropical cloud forests in the mountains where you will find the most species, he added: there are 600 species of ferns in the Amazon lowlands, versus 1,200 in the mountains of Bolivia. Species diversity is much more limited in temperate climates, he notes.
Sundue is fascinated by fern reproduction. Which is, well, different. Ferns have a two-stage reproductive cycle.
Mature ferns produce spores — millions of them. If the spores find a nurturing environment — moist and warm — they develop into an independent plant, but one that doesn’t look like a fern. It’s tiny, almost microscopic. This is the first stage of the fern, called a gametophyte. This tiny plantlet has its own root system, but it also has both male and female sex organs. The sperm produced by the male organs swim to the female organ and fertilize an embryo that grows into a new mature fern, called a sporophyte, that can then cast its own spores to the wind. The sporophyte is the plant most people are familiar with. If that isn’t complicated enough, most ferns can also spread through rhizomes, roots that generally grow across the top of the ground.
Sundue notes that fern reproduction isn’t passive. The first spore to fall in an area and begin growing produces chemicals that force other spores that land around it to produce only sperm. It’s a way of keeping away competitors. One question is, since the sperm swim to the embryo in water, how do they know where the other gametophyte is? The likely answer: chemical cues.
And it’s also interesting that some ferns can be self-fertile, or fertilized by other individual ferns of the same species, or in some other cases of different species. Ferns like to hybridize.
Reproduction through spores helped ferns survive and thrive after mass extinction events that killed off more complex species, said Massachusetts fern expert Donald Lubin. “They’re less edible than seeds and they travel farther,” riding the winds before drifting to earth, where they can bide their time before germinating.
Botanists monitoring the revegetation of Mt. Saint Helens in the aftermath of its 1980 volcanic eruption, were really interested to find a fern growing on the flanks of the devastated mountain. “But it was a particular fern unknown in Washington State,” Lubin said. “It was a Japanese fern. The spores can get into the jet stream and travel long distances.”
In addition to a method of reproduction that gives them an edge, ferns “also are not particularly good to eat. A lot of them have hairs and scales, kind of like armor, that make them unpalatable,” said Lubin. “They also grow in a spiral, the classic fiddlehead shape, designed to keep the growth tip surrounded by older, tougher tissue. And they contain toxins.”
Many ferns sport a complex array of chemical defenses that not only keep insects from eating them, but mammals as well, said Arthur Haines, research botanist for the Native Plant Trust.
The bracken fern, common along Maine roadsides and in clearings, produces anti-nutrients that bind to essential minerals in the body, preventing absorption of minerals and thus making the food ness nutritious, Haines said. Bracken fern also produces a hormone-like compound that causes insects to molt ahead of schedule, interfering with their development and killing them. And, bracken fern produces nectar that attracts ants, which discourage predation by other insects and mammals, he said. It is a fern of many lethal talents.
Bracken fern is one of Haines’s favorite ferns. And . . . he eats it. Many foragers do, but by no means as many as forage for Ostrich ferns, he said. Ostrich ferns, also known generically as “fiddleheads,” are considered something of a spring delicacy in northern New England. In the early spring when bracken fern is just emerging and hasn’t yet ramped up the production of toxins, Haines picks the fiddleheads and boils them six to seven minutes, deactivating their defensive chemicals, and serving them with butter. “They have this brief window at the beginning of the year when they are tender and their defenses can be overcome by cooking,” Haines said. “When you’re cooking them, it smells like cherries.”
There are 61 species of ferns in Maine. Most are understory plants, said Haines. Bracken fern likes more sun than most, but even it will tolerate shade. There’s a fern for almost any site, he said, from the very wet to the dry. There are some species that prefer cliff faces. Most prefer forests, particularly deciduous forests — with sugar maples, ashes, lindens — “those with moist soils, sometimes rocky, those are where the highest diversity of ferns is to be found” in Maine, said Haines.
There are 79 species of ferns in New England, not counting hybrids. But many are not all that common.
Levine’s pocket guide deals with the 28 species most people are likely to encounter across a broad swath of northeast North America, from Pennsylvania east and north into Canada. It was important to narrow things down to help the ease-of-use factor, she said. Fern fanciers will recognize the names of many of the species she deals with, including maidenhair, ostrich, royal, cinnamon, bracken, Christmas and hay-scented ferns.
As an aside, the hay-scented fern is sometimes considered a pest. In some cases, where the forest is clearcut or deer have thinned the undergrowth severely, hay-scented fern can take over, muscling out other plants and making it difficult for trees to regenerate.
It can seem more difficult to identify ferns than, say, flowers, but that may be because people aren’t as familiar with them. Levine devised her own system to take people through the process, with a panel of fern experts helping to refine it. Her system divides fern species into “groups” depending on how many times the “blade” is cut and whether the fern grows in a vase-like cluster. That alone will generally narrow the field to four to six in each group. Then the reader can use silhouettes of fern blades to narrow it down.
Where a fern is growing is key to identifying it, she said. “Some ferns only grow in certain habitats, like sensitive fern or ostrich fern or cinnamon fern.” Many fern species need moisture and richer soils, like ostrich fern. Others, like rock polypody (translation: many feet), can literally grow on bare rock.
In addition to habitat, Levine gives tips for identifying each type of fern, explains how to avoid confusing it with lookalike species and provides some interesting facts about each species. The guide is illustrated with line drawings by professional artist Briony Morrow-Cribbs that add a vital visual dimension when it comes to identifying ferns.
Another thing to note about ferns, particularly in the Northeast, is that, Haines’s tendency to eat bracken fern aside, only one species is really of commercial value, the Ostrich — or fiddlehead — fern, which grows in alluvial soils and is harvested in early spring — “fiddlehead season.” And the market there is, well, niche to say the least. Ostrich ferns are now being overharvested in many places. Lubin notes that a few fern fronds end up in florists’ flower arrangements, but that’s about it.
Where Lubin sees value is in ferns’ beauty.
Ferns have a “very delicate design,” he said. “They add a whole new level of texture to the visual experience” of the forest. “A lot of people just like to see them. They remind me of a past time in the history of the earth.”
For Levine, the maidenhair fern, the one that started her on a five-year guidebook project, is still her favorite. Again . . . “Because it is so beautiful. It’s different from every other fern. It’s very fine.” Actually, ostrich fern is also a favorite. And . . . Well, you get the idea.
But it’s not just ferns’ beauty that Levine admires. It’s their toughness. Their kind have lived through five extinction events, including some that wiped out most of the species on earth, including the dinosaurs, she said. “Ferns are survivors. They look fragile, maybe. But they can take over a bank or some bare soil that nothing else thrives in. In terms of climate change, I bet the ferns are going to survive.”
Joe Rankin writes on forestry, nature and sustainability from his home in New Sharon.