Mushrooms Fascinate Gourmets and Ecologists : Delicacies: Flavorful fungi of field and forest occupy a vital niche in nature, scientists say. Some may be sensitive indicators of the health of entire ecosystems.

Death cap. Bear’s head. Witch’s butter. Ma’am on a motorcycle. Destroying angel. Black earth tongue. Satan’s bolete.

No, these are not the names of neighborhood motorcycle gangs. But they might be in your neck of the woods. The monikers refer to small, unobtrusive, commonly found forest or field fungi--in other words, mushrooms.

Mushrooms have fascinated, mystified and fed mankind since the beginning of time. Sometimes they even make the evening news, as they did when scientists recently discovered a gigantic mushroom living in Michigan’s Upper Peninsula.

Ecologists studying the complex interrelationships of living organisms say that mushrooms occupy a vital niche in field and forest. And some mushrooms may be sensitive indicators of the health of whole ecosystems.

“Mushrooms and other fungi have several important roles in nature,” said Dr. Geoffrey Parker, a research ecologist at the Smithsonian Environmental Research Center in Edgewater, Md. “They help things grow, they are a source of food, they decompose organic matter and they debilitate, infect and kill organisms.”

But what most people prize about mushrooms is their role as delightful delicacies. When early peoples hunted wild beasts for food, historians say, they probably also stopped to gather mushrooms. Kings of ancient Babylon dined on truffles brought in from the African deserts. Roman emperors so valued mushrooms that they cooked them in special silver vessels called boleteria . Ordinary citizens were forbidden to eat them.

Japanese cuisine is famous for its use of black mushrooms called shiitake and the fragrant matsutake. The ancient Japanese raised matsutake-gathering to an art, involving elaborate dress, speech and behavior. Today, however, the matsutake has been “hunted” to near-extinction in Japan and must be imported from Korea and the United States--at the exorbitant cost of $40 to $60 per mushroom.

Mushrooms continue to hold a special place among many peoples of the world. “In Eastern Europe particularly, mushrooms are revered,” said Maggie Rogers, co-editor of Mushroom, The Journal of Wild Mushrooming. “It’s an attitude that Americans don’t fully understand. I liken it to how Californians feel about their cars.”

There are an estimated 30,000 species of fungi, a category that includes mushrooms, molds and rusts. Some are harmful. The Amanita group of mushrooms, for example, contains some of the most deadly of all mushrooms, such as Amanita phalloides , or death cap, the most poisonous mushroom in North America. Ironically, Amanitas --some with red caps with white spots--are also among the most beautiful mushrooms. Other fungi are beneficial: Penicillin is derived from fungi, for example, and yeast fungi have been used for centuries to ferment food or drink.

Mushrooms are high in protein, good sources of vitamins and trace minerals and low in calories. Each has a particular flavor, fragrance and texture. In fact, mushroom gatherers will argue the merits of one mushroom over another, much like wine connoisseurs debate merlots and pinot noirs.

“To me, mushrooms are emotion-laden because of their smell,” said Roger, an avid mushroom gatherer. “I use scent as one way to identify a mushroom, though most of the handbooks do not. Each smells slightly different, from fruity to damp and spicy.”

Mushrooms are an unreliable food source because they do not always appear in the same place or in the same amounts from year to year. Interestingly, a mushroom in one part of the world may not be safe to eat in another. The snow bank mushroom, for instance, is edible in the Western United States, but toxic in Europe.

To propagate, mushrooms release spores so tiny that 10,000 can fit into a space the size of a pea. Once released, only a small percentage of spores will germinate for they must land in an area where temperature and humidity conditions are ideal for growth. Although the Chinese cultivated wood ear fungi as early as 300 BC, European cultivation did not start until the 1700s.

Mushrooms have been grown commercially in the United States for less than a century, but it has not been easy. Most edible mushrooms cannot grow outside their natural habitat and must be hand-gathered.

Despite a mushrooming interest in fungi, most casual gourmets would be surprised to learn that mushrooms are only the fruiting, or reproductive, part of the organism. Most of the mushroom is hidden below ground, a network of tiny root-like threads or filaments called mycelium.

The recent discovery in Michigan was a 220,000-pound fungus called Armillaria bulbosa --the fruit are called honey mushrooms--which covers more than 30 acres underground. This one fungus was spawned by a single fertilized spore some 1,500 to 10,000 years ago, and today is believed to be one of the largest and oldest living organisms on Earth.

“One of the most important roles of some mushrooms is to form a symbiotic, or interdependent, relationship with the roots of trees,” the Smithsonian’s Parker said. “The mycelium of these mushrooms extends the tree’s surface area to draw in much larger amounts of phosphorous and water. This helps a tree grow even in poor soil.”

In return, Parker said, the mushrooms obtain carbon compounds, or food, from the tree’s root tissues. Some mushrooms are so dependent that they cannot survive by themselves; others form relationships only with certain trees--an important identification clue for mushroom gatherers.

This relationship between mushrooms and trees was uncovered in the late 1880s by German scientist A. B. Frank. Frank dug up trees and found fine threads that were connected to mushrooms on the surface surrounding the tree’s roots. He called the interrelationship mycorrhiza or “fungus root.” When mycorrhizae are present, Parker said, trees seem to grow much faster and are healthier. Foresters actually inoculate trees with selected species of mushrooms, since many trees will not grow without them.

“Mushrooms play a second role in the environment as well,” Parker added. “As nature’s recyclers, they help decompose organic matter and return it to the nutrient cycle.” Some woods, for example, would not decompose rapidly without the help of mushrooms. Scientists refer to these mushrooms as “saprophytic.” They live on dead or decaying plant material, such as pine needles, leaves or logs. Many are so specialized that they will live only on certain kinds of materials.

Some mushrooms and fungi are parasitic. Honey mushrooms, for example, can sometimes be seen paralleling the roots of an oak tree. Clusters of honey mushrooms can smother a tree’s base or trunk, rot the tree’s interior and cause commercial loggers to lose millions of dollars in damaged timber.

In addition to their commercial and culinary value, mushrooms play another role. “Mushrooms have been around for the last couple million years and they are a sensitive indicator of changes in our environment,” said Dr. Denis Benjamin, a pathologist at Children’s Hospital in Seattle and education chairman of the Puget Sound Mycological Society.

“What the data today show is disturbing,” he said. “The variety, number and size of mushrooms have declined dramatically in the last 200 years. There may be multiple causes for this--acid rain, pollution, even forestry practices. Most ecologists agree that habitat destruction has been particularly overwhelming during the past 20 years.”

Scientists continue to search for causes for the disappearing mushroom. Field surveys carried out in the Netherlands from 1912 to 1954 recorded an average of 71 species of fungus. From 1973 to 1982, surveys turned up an average of only 38 species. More recent field work tells the same story.

Ecologists also worry about changes seen in the pattern of association between fungi and trees. Normally, as a tree gets older, one species of fungus steadily gives way to another. But scientists have recorded middle-aged trees with old-age fungi. These trees drop their leaves more readily and some die prematurely. In other words, the condition of a forest’s fungi population could provide an early warning signal about the health of the forest’s trees.

“Mushrooms depend on their immediate environment for survival,” Benjamin said. “Unlike animals, they can’t move if conditions change. Their decline could provide an important clue to changes in our forests and in whole ecosystems.”