Introduction to Mushroom

Mushroom, any of the fleshy fruiting bodies of various types of fungi. Mushrooms can be classified as nonpoisonous and poisonous. Poisonous mushrooms are sometimes called toadstools.

Mushrooms can be found in many different places, such as damp woods, open pastures, and lawns in the city. They seem to appear suddenly, as they grow very rapidly during a moist warm night and quickly become full grown. They decay as quickly; some last a few hours, others a few days.

Mushrooms have a great many shapes and colors. The most familiar ones are shaped like umbrellas. Other shapes resemble funnels, stars, balls, honeycomb, pieces of coral, or bells. Mushrooms come in almost every color.

MushroomsMushrooms grow very rapidly during a moist, warm night.

Development and Growth

Mushrooms, like other fungi, have no chlorophyll and cannot manufacture their own food. Most mushrooms get their nourishment from decaying organic matter, such as wood, humus, and manure. These mushrooms are saprophytes. A few mushrooms get nourishment, at least in part, from living plants. These mushrooms are parasites.

A typical mushroom has tiny structures called basidia, which produce unicellular reproductive bodies called spores. Under favorable conditions of moisture and temperature, a spore germinates and develops into a mass of white filaments, called a mycelium, which spreads through the organic matter. A mycelium grows for years, lying dormant in winter and dry periods, becoming active when it is moist and warm. Two filaments, or hyphae, of two different mycelia fuse sexually and produce a new mushroomthe fruiting body, or basidiocarp, of the fungus.

Typically, a small, forming mushroom has a rounded shape and is called a button. The button grows rapidly to become the stem and the cap, which together look like a small umbrella. On the underside of the cap are numerous bladelike structures called gills. The gills are initially covered by a membrane, but as the cap grows, the membrane breaks. (The membrane stays attached to the stem below the cap, forming a collar called the annulus.) The gills are lined with basidia, which shoot mature spores into the air to be carried away by the wind. Mushrooms of certain species have pores, or small holes, instead of gills; the basidia are located in the pores.

Gills sometimes change color as the mushroom matures. As the meadow mushroom, a species common throughout North America, matures, its gills change from white to pink to brown. The meadow mushroom is grown commercially and usually harvested before the gills become visible.

Some mushrooms, such as those of the genus Amanita (a group that includes some of the most poisonous species), are completely covered with a membrane when young. As the mushroom grows, the membrane breaks and forms a cuplike structure (the volva) at the bottom of the stem.

Commercially, mushrooms are grown indoors in dark, damp placescellars, caves, abandoned mines, and specially designed buildings. Pieces of specially grown mycelia (called spawn )are placed in beds or trays containing a pasteurized compost of manure or mixture of chopped corncobs, hay, and chemical fertilizers. After five or six weeks the mushrooms appear.

Nonpoisonous Mushrooms

There are perhaps a thousand kinds of mushrooms that are not poisonous. Many of these are edible. Mushrooms are a good source of vitamin B2 and certain minerals, and they are low in calories. In addition to the meadow mushroom, some of the well-known nonpoisonous mushrooms are:

Horse Mushroom

This species resembles the meadow mushroom but is larger and coarser. The flavor is considered excellent.

Coral Mushroom, or Clavaria

This genus includes some of the larger forms of the stag horn, or fain-club, fungi. Coral mushrooms grow upright in fingerlike clumps, resembling yellow or white coral. They may be found in late summer and early autumn in moist woody places.

Oyster Mushroom

This mushroom is named for its flavor. It is found in clusters on logs and on dying or dead hardwood trees. The stalks are short and laterally attached; the caps are white to ashy gray with white gills beneath.


This is the largest of the genus called inky caps, or ink caps. The shaggymane is often six inches (15 cm) tall, with a cylindrical cap three inches (7.5 cm) long and one and one-half inches (4 cm) in diameter. It springs up overnight on lawns after a warm rain. By the end of the day it has matured and the gills and some other parts of the cap have turned into an inky black liquid. It must be picked just before maturity and cooked promptly.


No puffball is known to be poisonous, but some are not eaten because of flavor or texture. When a mature puffball is struck it will give off a cloud of dust, which is composed of dark brown spores that have developed inside it. Puffballs should be eaten only when the insides are white and solid. Also, only large ones should be picked because certain poisonous mushrooms pass through a button stage in which they resemble a small puffball. Several species are eaten. The largest is the giant puffball, which has been known to reach a diameter of more than three feet (90 cm).

Fairy Ring Mushroom

This species is rather small, but it is popular because it is found in abundance and has a nutlike flavor and good drying qualities. It is buff in color and grows chiefly in open grassy places, often in circles called fairy rings. These rings are caused by the outward growth of the mycelium year after year in an increasingly larger circle. Fairy rings may be formed by other species of gill mushrooms, including the meadow mushroom.

Shiitake, or Black Forest Mushroom

This is a wild Japanese mushroom that is popular in the United States because of its smoky, garlic-like flavor. The cap is up to three inches (8 cm) wide and is tawny to dark brown. It is found on conifer and hardwood stumps.


There are several species with excellent flavor. The whitish stalk supports a cap that is conical or cylindrical, black to olive-gray, and pitted or honey-combed. The morel is found in early spring in orchards and deciduous woods.


This relative of the morel grows underground. It is found primarily in Europe, where pigs and dogs are trained to locate it by its pungent aroma. It is then dug up with a small hoe. Truffles are considered a delicacy.

Poisonous Mushrooms

Illness can be caused by several species of mushrooms, but only a few are deadly. Listed below are some of the more common poisonous species.

Destroying Angel

This is the most poisonous mushroom. It is a gill fungus that is relatively easy to distinguish from edible species after a careful examination. Yet 90 per cent of all the deaths from mushroom poisoning are estimated to be caused by this species. The destroying angel is white throughout and has a distinct cup at the base of the stalk and a well-developed ring below the cap. The spores are white and the gills are never brown. Its poison, phallin, separates the corpuscles in the blood from the serum.

Fly Agaric

This mushroom is deadly only if eaten in large quantities. It grows as much as one foot (30 cm) tall in woods and along roadsides. The top of the cap is straw yellow to reddish orange, spotted with white or pale-yellow warts. The gills are white or pale yellow. One of its poisons, muscarine, paralyzes the nerves controlling heart action.

The fly agaricThe fly agaric mushroom is deadly if eaten in large quantities.

This is an orange-yellow mushroom that grows in clumps on stumps or logs in the woods. It is luminescent, giving off a weird glow on rainy nights. If eaten, it will cause violent illness, but it is not considered deadly.

Panther Fungus

This is a yellow, gray, or brownish species that produces a poisoning similar to, but milder than, that of the fly agaric. The volva is usually smaller in the panther fungus than in other species.

Emetic Russula

This mushroom causes violent illness. Its cap is usually deep red.

Despite the danger, small amounts of fly agaric or other poisonous species are partaken of by certain people in Siberia and Mexico to induce visions or hallucinations during religious or orgiastic rites.

Most mushrooms belong to the class Homobasidiomycetae of the division Basidiomycota. Morels and truffles belong to the class Euascomycetae of the division Ascomycota.

The meadow mushroom is Agaricus campestris; horse mushroom, A. arvensis. Both belong to the family Agaricaceae.

Coral mushrooms are of the family Clavariaceae.

The oyster mushroom is Pleurotus ostreatus; fairy ring mushroom, Marasmius oreades; shiitake, Lentinus edodes; jack-o'-lantern, Omphalotus olearius. These four belong to the family Tricholomataceae.

The shaggymane is Coprinus comatus of the family Coprinaceae.

The giant puffball is Calvatia gigantea of the family Lycoperdaceae.

Morels belong to the families Helvellaceae and Morchellaceae.

The truffles belong to the genus Tuber of the family Tuberaceae.

The destroying angel is Amanita virosa; fly agaric, A. muscaria; panther fungus, A. pantherina. These three are of the family Amanitaceae.

Emetic russula is Russula emetica of the family Russulaceae.