Become a fern expert in one easy lesson

By Tom Seymour | Jul 09, 2017
Photo by: Tom Seymour Interrupted fern

Ferns. They’re all around us, but how many can identify more than one or two species? But learning one fern from another is really easy and being armed with the proper knowledge might just make you a legend in your own time.

Everyone who recreates outdoors encounters ferns. Ferns are in the woods, along our roads and even in our backyards. It seems kind of a shame to have such close contact with these primitive plants and not really know much about them.

That will change, though, after you are done reading this column. But first, while you’ll easily learn all about the five ferns mentioned here, in order to truly become a fern expert, you’ll need a good fern book. The world abounds in books about ferns, but one book in particular stands head-and-shoulders above the rest.

The title is, "Ferns of Northeastern United States," the author is Farida A. Wiley and the publisher is Dover Publications Inc., New York. This book has great descriptions as well as excellent, detailed line drawings. And it’s inexpensive. My copy, which I bought online, cost $3.95. Even better, Wiley has included vascular bundle patterns. These are what we see as little dots and squiggles on a cross-section of a fern stem, or stipe.

Vascular bundles are similar to veins in our bodies in that they carry water and nutrients throughout the plant. And each fern has a different vascular bundle pattern. So after reading about a fern you wish to identify, match it to the line drawings in the book and as a final check, compare vascular bundle patterns. To do this, just cut the stipe cleanly with a sharp knife and look closely at the cross-section for a dot pattern. It couldn’t be simpler. So let’s take a look at our five featured ferns.

1. Ostrich fern

While all ferns go through the fiddlehead, or crosier phase, only one fern has good, edible fiddleheads, and that is the ostrich fern. So popular are fiddleheads that locations of prime spots are shrouded in secrecy. And that’s how some people want it. But in fact, ostrich ferns are common and abundant. I often spy patches of ostrich ferns while driving down the road. That’s because I know how to identify the fern at its mature stage. You can do the same.

The entire fern, as a package, is called the “frond” and it grows over three feet long. Visually, the blade is narrow at the bottom and wider in the top third. It quickly narrows again at the very top. In other words, the overall shape resembles a long, skinny teardrop.

The stipe itself is dark green, smooth and a wee bit shiny. The emerging fiddleheads are covered with a brown, papery parchment which must be removed before preparing for the table. The stipe is deeply grooved and a cross-section somewhat resembles a horseshoe.

The vascular bundle pattern shows two backward S shapes, one on either side.

And while ostrich ferns abound in the wild and are easily transplanted, seed companies now sell live plants, and these are suitable for foundation plantings.

To become adept at spotting mature ostrich ferns, I recommend going to a known fiddlehead patch and examining the adult ferns. It might help to take a digital image for later reference. Then, after you know the appearance of ostrich ferns in summer, you’ll find it easy to spot them as you travel around, either on roads or trails.

2. Interrupted or Clayton’s fern

The overall shape of the frond is similar to that of ostrich fern, but with one distinct twist. Interrupted ferns are, well, interrupted. That is, the sterile pinna, the little leaf-like appendages that grow on both sides of the frond, are absent from the midsection of the frond and in their place grow the much smaller and insignificant-looking fertile pinna, thus giving the impression of a blank space on the stipe.

The stipe itself is covered with light-brown, wooly hairs, but these drop off when the fern matures. The vascular bundle resembles a hooked crescent.

And as with ostrich ferns, interrupted ferns are easily spotted, even from a considerable distance.

3. Hayscented fern

Hayscented ferns have an evenly-tapered frond, wider at the bottom and long and narrow at the top. The pinna, except at the very base, are placed slightly alternate on the stipe. In other words, instead of each side being a mirror image of the other, pinna on one side will always be places slightly above the pinna on the other side. This continues the length of the stipe.

Hayscented ferns grow to 2 feet long, considerably shorter than ostrich or interrupted ferns. The light-colored vascular bundles appear, in a cross-section, as an upside-down U.

Hayscented ferns are well-named, since bruising them releases the sweet scent of new-mown hay. Hayscented ferns are abundant in coastal Maine, and on our offshore islands, entire fields are covered with them.

Walking along trails lined with hayscented ferns, I always swipe a few ferns with my walking stick in order to release the scent. This just adds to the pleasure of my outdoor trips. It’s little things such as this that make trips in our Maine outdoors so memorable.

4. Bracken or brake fern

An aggressive colonizer, bracken fern quickly fills in any newly opened woodland area. Some people eat bracken fern fiddleheads, but research done by the Japanese indicates that they are carcinogenic. Besides that, I tried them and they gave me cramps. Definitely not worth eating. But still, it pays to know them.

In the highlands of Scotland, people cut bracken for agricultural use. A catchy pipe tune, “Cutting Bracken,” presents a challenge for amateur pipers.

But here in Maine, bracken goes largely unnoticed. In fact a large majority of the population is unable to put a name to this durable fern. But you will now know it, by noting the following characteristics.

Bracken fern fronds can grow to an amazing 4 feet in length when measured in their entirety. The blade, which is three-parted and forms a triangle, grows at a right angle to the stipe. So here we have a fern with a naked stipe, with three separate blade sections growing out at right angles from the top. No other Maine fern has this configuration, which makes identification a snap.

5. Sensitive fern

Sensitive fern is so-called not because it is easily offended, but rather, because it is the first fern to succumb to an early frost. While other ferns continue to thrive, sensitive fern quickly fades away because it is frost-sensitive.

The frond contains an erect single blade. The flat portion of the blade is webbed-appearing near the top, in that the flat part of the green, leafy section of the pinna appears to be punched out, with a rounded valley near, but not touching, the stipe. This can vary, however, from one fern to another.

Vascular bundles join together at the top of the stipe. A cross-section of the stipe resembles an igloo, half-round, with a flat base. The vascular bundle design incorporates two, opposite-facing semicircles.

And with this, you can now go out and identify five of our common ferns. But I suggest you send for the Farida Wiley book, since it will help you to become a true fern expert.

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