Mushrooms have been around since life originated on Earth. In fact, much of life on this planet depends on fungi, for they are the great recyclers of the forest, converting fallen plant matter into precious soil. Mushrooms' modern uses are exciting: from those that transform agricultural waste products into inexpensive but strong composite building materials that can be reused as garden mulch, to pesticidal fungi that trick insects into eating them, to mushrooms that can break down the neurotoxins used in nerve gas.
Culturally, fungi have an important history of uses. Pharaohs ate mushrooms as a delicacy. Greeks believed them to be a source of strength. The Chinese regard them as health food. There are over 14,000 types of mushrooms in the world, out of which about 3,000 are edible; and of those 700 have known medicinal properties. Around the world, we feast on fungi for their flavor, texture and nutritional and health benefits.
Mushrooms are fungi that belong to the phylum Basidiomycota. What we call a mushroom is actually the reproductive structure, or the fruiting body, of the fungus. A typical mushroom has an umbrella-shaped cap with a stalk and gills on the underside. Caps vary widely in color and shape.
In nature, mushrooms grow wild on moist, rich soil or on the barks of trees. Mushrooms are mostly aerial except in the case of the exotic truffle, "the diamond of the kitchen," which produces an underground fruiting body. Do not go into nearby woods to collect mushrooms unless you know how to identify edible mushrooms, because a fair number of wild mushrooms are poisonous, some even deadly. The best approach is to go out mushroom hunting with a knowledgeable guide.
Edible mushrooms are readily available at grocery stores, farmers' markets and from mushroom farms. The most popular cultivated edible mushrooms are Agaricus bisporus, including white, crimini and portobello. Portobello are giant--about six inches in diameter--mature crimini mushrooms. Other cultivated species include shiitake, porcini, maitake, hen-of-the-woods, oyster and enoki.
The shiitake, native to China, is known for its healing properties. Aromatic oyster mushrooms grow on fallen, dead hardwood in forests and have a scallop-shaped cap with a delicate, anise-like flavor (these can spread out to 18 inches in diameter, with thick flesh). Cultivated oyster mushroom caps come in a variety of colors: gray, blue, yellow, pink and white. Porcinis, with their earthy, nutty flavor--considered the king of edible mushrooms by the Italians--live in a symbiotic relationship with trees, very common in pine forests and chestnut woods all over the world.
The cheapest mushrooms are white and brown crimini. Truffles are the most expensive; a pound may cost a couple of thousand dollars, and a single truffle may weigh one to three pounds! One can cultivate mushrooms indoors at home, providing the right conditions. Spores and kits to grow mushrooms are commercially available.
Edible mushrooms are extensively used in cooking. You can easily incorporate them in soups, sauces, vegetable medleys, pastas, rice dishes, etc. Clean mushrooms with a soft brush prior to cooking. Never soak them in water; if you must, wipe them with a damp paper towel. Optionally, remove the stalks, which may be used for preparing stocks along with other vegetables. Fresh mushrooms do not last long in a refrigerator. Dried mushrooms can be reconstituted by soaking in hot water for ten minutes. Cook in a heavy skillet on low heat. Herbs and spices may be used to enhance flavor. Food, in addition to being nutritious, should be colorful, flavorful and aromatic.