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peterson field guide ferns northeast

Fern Field Guide, a Classic Revisited

by Bee Mohn

Peterson Field Guides set the standard in readily available books that help us learn about the world we live in. They are bibles of nature, earth encyclopedia, seemingly written in bedrock. So what's to revamp in a classic?

Plenty, according to Elizabeth Farnsworth who, along with Cheryl Lowe, recently authored and revised Ferns of Northeastern and Central North America, Second Edition. This daunting re-creation, originally by Boughton Cobb, took two years for the pair to complete and the book is now going into its second printing.

Elizabeth Farnsworth is senior research ecologist at New England Wild Flower Society (NEWFS) and a Bullard Research fellow at Harvard University. Cheryl Lowe is director of horticulture at NEWFS.

The new full-color edition, 50% larger and still pocket-size, contains photographs and additional drawings, revised nomenclature and key, an updated bibliography, a botanical glossary, and sections on fern ecology, evolution, conservation, and how to plant and propagate ferns and integrate them into the garden. It also describes about 40 additional species. A cadre of experts contributed expertise, knowledge, photos, and reviews. “They really leapt in with both feet," says Farnsworth.

“With new genetic information we've been able to tell whether certain ferns are a separate species or a subspecies, for instance."

Since Cobb's book first came out 49 years ago, it is our understanding of ferns that has evolved rather than the fern species themselves, explains Farnsworth. Over the last half-century, more sophisticated genetic and morphology studies have revealed new information about the evolution, distribution, and relationships of ferns and fern allies and the recognition of naturally-occurring hybrids.

“Over the last 50 years you would expect to see new hybrids arising, but I can't point to a specific example of a brand new species on the landscape," says Farnsworth. “Ferns are as likely as other plants to evolve. A lot of flowers pick up on climate change. We see real changes in flowering times of flowering plants. A lot now are blooming several days to several weeks earlier than at the beginning of the 20th century. Whether that is an evolutionary response or a very plastic response, we aren't sure. Ferns are adaptable too, but nobody to my knowledge has documented whether ferns are emerging earlier or unfurling earlier."

Others, such as sensitive fern (Onoclea sensibilis), need to get their feet wet but deal flexibly with changes in rainfall. This fern was found to be native to the northeastern US and also eastern Asia. “There are other environmentally-caused changes we have been seeing. Isoetes (quillwort) tend to be real sensitive to acid rain. In Europe several species have disappeared," she notes.

In scientists' quest for more information on the evolution of ferns, they would also look for shifting ranges of certain species that are limited in their distribution by temperature. “You could hypothesize that if temperatures started to warm up here, they (more southern ferns) would expand their range northward. We need to pay more attention to ferns."

Indeed. Although poaching used to be a major cause of destruction, today's concern is loss of habitat. In Massachusetts alone over 40 acres of habitat is lost every day, according to a Massachusetts Audubon study. “That means in the course of a year a lot of ferns are going to be destroyed. In the Northeast, one-third of fern species are on one state list or another," Farnsworth says.
"That book was in my backpack 365 days a year. I knew that there had been a lot of new name changes." - Farnsworth

In 1993, a new nomenclature for ferns was described in The Flora of North America Volume 2, which Farnsworth and Lowe consulted for the guide. Scientific knowledge is ever-changing, like recently, new genetic studies clarified relationships between ferns and fern allies. “There had been major new work, just as we were going to press, that showed a completely new phylogeny of ferns," Farnsworth says. She and Lowe managed to include a new family tree of ferns in the guide.

“Boughton Cobb was using the older names. I knew that the keys really needed an update. One key first relied on silhouettes and I've worked with a lot of folks pouring through the keys and knew there were places where things were ambiguous. I knew it would be so nice to have accurate characteristics. It's critical to have accurate drawings when only a simple characteristic means the difference between species. We have photos to see ferns in color and in their habitats. They are green, but different shades of green. The accompanying photos give a better gestalt for the whole thing. To me it's one of the best illustrated fern guides out there."

So how does one get to redo a classic?

A few years ago, Farnsworth and Lowe's stars aligned -- timing and positioning being everything. When NEWFS celebrated the “Year of the Fern" in 2003, they each contributed articles on fern conservation, evolution and life cycles to the organization's annual magazine. At the same time, on the other side of Massachusetts, publisher Houghton Mifflin Company was thinking of revising the book. They had already worked with NEWFS and seen the pair's articles. Lowe and Farnsworth were commissioned.

“Cheryl and I had never written a book before, so it was a serious leap of faith," says Farnsworth. “Fortunately we like to write, work together well, and are hyper-responsible. The ability to work with Cheryl from point one to the bitter end was wonderful. She is just my hero.

“People are doing more research on ferns. With advances in science we are understanding more about genetics. We are sequencing fern genomes and understanding how closely related different fern species are and their evolutionary relationships. The more science compiles detailed data about how ferns reproduce, we'll better understand their habitats and environmental factors that affect their growth. There's more people on the problem."

Fiddlehead-picking advice: Once a fern puts out its fiddleheads in spring, that's all it will produce for the entire year. If you pick them all, the plant cannot photosynthesize. This can eventually lead to the fern's death. “Imagine plucking each new leaf off your maple sapling. They can't send energy down to the roots if you do that year after year."

If you do pick fiddleheads, leave a few for the plant. Cut the stems off gently so as not to disturb the root system.

** All drawings and photo courtesy of Elizabeth Farnsworth
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published December 10, 2005

Photos to enlarge

Megaspore of the quillwort species, Isoetes lacustris

Botrychium matricariifolium (Daisyleaf moonwort)

Cone of the horsetail, Equisetum x ferrissii

Elizabeth Farnsworth in Newfoundland,

Cheryl Lowe, Courtesy of Lisa Mattei

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