Ferns past and present

StoryImage( ‘/Images/Story//Auto-img-11206720471276.jpg’, ‘Photo by Dr. Robert A. Hedeen’, ‘Fiddleheads of ferns emerge from the ground in the spring and early summer.’);
StoryImage( ‘/Images/Story//Auto-img-11206722392625.jpg’, ‘Photo courtesy of www.home.att.net’, ‘Found in a coal mine, this petrified fern shows no decaying—meaning rapid burial. Huge quantities of vegetation were amassed and buried before they could rot to form the immense coal fields found all over the globe.’);

During the Carboniferous Period of the earth’s history, some 300 million years ago, stately, fern-like trees towered over much of the surface of the planet. At that time, great stretches of our continent were covered by shallow brackish seas, and on their shores grew ferns in the warm, moist air. All indications are that the Carboniferous period was very cloudy, and this cover protected the delicate texture of ferns from the harmful direct rays of the sun. Heavy rainfall encouraged their growth.

Most of these huge tree-like ferns had evolved from true ferns, very similar to the ones we have with us today. The tree ferns produced seeds for reproduction, rather than spores as do true ferns. Both had evolved a vascular system where food and water could be transported to all parts of the plant, and this advancement, along with reproduction by seeds, enabled this group of primitive plants to evolve into the true seed plants that dominate the flora of the earth today. As the eons rolled by, however, the earth’s climate changed, and most of the tree-ferns became extinct. They died and toppled into the ooze and became more compacted in the substrate as millions of years passed. They eventually came to make up most of the coal, which now releases in our furnaces the energy of the sun originally trapped by the plants. Hidden deeply in the inky folds of coal are imprints of these fern-trees, and paleo-botanists have described hundreds of these prehistoric forms.

The true ferns that were associated with the seed-producing fern-like trees lived on, however, as the climate grew colder. For more than 200 million years, they have survived and flourished. Now where their huge ancient relatives once towered, the comparatively small true ferns clothe a cooler, sterner earth. There are about 9,000 different species of true ferns worldwide, and they can be found flourishing in many different ecological habitats.

There are two phases in the life cycle of a fern: an asexual and a sexual phase. The fern we see growing in nature or in a basket decorating our premises represents the sporophyte, or asexual generation. At certain times of the year, spores are produced on the undersides of the fronds and are shed far and wide by the wind. The spores contain only one-half of the normal chromosome number of the plant. If a spore lands in the right environment, it grows into a tiny structure called the prothallium. The equivalent of sperm and eggs are produced by the prothallium, and they unite to form the next sporophyte generation. With the union of the two gametes, the normal chromosome number is restored.

As the new sporophyte emerges from the ground, the tip is coiled and resembles the head of a bass fiddle. Fiddleheads, as they are called, are relished by some gourmands, and some may resemble asparagus in taste. But fiddlehead neophytes, beware. Some ferns contain substances that upset the human gastrointestinal tract, but none are apt to cause serious illness in humans. Identify the fern fiddlehead with the aid of a field guide before you put it on the table. There are three species of ferns in this area, the fiddleheads of which are considered imminently edible: the ostrich fern, the lady fern, and the bracken fern. Of these three, the bracken is the more common in the Rock River Valley

There is only one species of bracken fern (Pteridium aquilinium), and it grows widely across the continent from Labrador to Alaska southward. The vigor, fertility, and ruggedness of the bracken make it the most familiar of North American fern, especially as it is among the first to thrust its fiddlehead above the ground in the spring. New fronds are produced until the first hard freeze of the year. The dark green fronds are stiff, rugged, and reddish at their base. Unlike many of this continent’s shade and moisture-seeking ferns, the bracken frequently can be found in dry, open spaces.

Though the bracken fern is known to contain a mild carcinogen called ptaquiloside, its shoots are a traditional food in Japan, Korea, and China. The cooked shoots are excellent in soups, pasta, casseroles, and many Oriental dishes. Studies have shown, however, that eating a bracken fern fiddlehead now and then is no more dangerous than drinking a cup of coffee or eating a charred T-bone steak. There are millions of Chinese, Koreans, and Japanese who can vouch for that.

Various Indian tribes and early settlers used the bracken fern to treat the following conditions: lung and liver ailments, parasitic worms, relief of digestive gas, cramps, and headache. But, even with the sky-high price of drugs and medicines these days, I doubt if your physician will prescribe bracken fern for any ailment you may have.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

From the July 7-12, 2005, issue

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