Every mushroom hunter should be familiar with the three most dangerous groups of fungi. These are the amanitas, the false morels and a catch-all category known as little brown mushrooms (LBMS). Mushrooms in these groups cause virtually all the fatal mushroom poisonings in the United States, with amanitas alone accounting for 90 percent of mushroom-related deaths. The pictures and descriptions on the following pages will help you avoid them.

There also are hundreds of other mushrooms that will cause anything from a mild stomachache to severe physical distress-including vomiting, diarrhea, cramps and loss of coordination. Two common poisonous mushrooms of this type, the jack-o'lantern and the green-spored Lepiota, are described here. Although the symptoms of poisoning from these mushrooms may be alarming, they usually pass in 24 hours or less with no lasting effects. You should, however, notify your doctor immediately if you suspect mushroom poisoning of any kind.

There is no quick and easy test that will separate edible from poisonous mushrooms-including peeling the cap, testing with a silver spoon, checking for insect damage or any other folk method. To avoid mushroom poisoning, you should follow these five rules:

  1. Identify each and every mushroom you collect, and only eat those whose identification you are sure of. When in doubt, throw it out.
  2. Strictly avoid: any mushroom that looks like an amanita (parasol-shaped mushrooms with white gills); all little brown mushrooms; all false morels.
  3. Some people are allergic to even the safest mushrooms. The first time you try a new wild mushroom, it is important that you eat only a small amount and wait 24 hours before eating more.
  4. As with other foods, rotting mushrooms can make you ill. Eat only firm, fresh, undecayed mushrooms.
  5. Most wild mushrooms should not be eaten raw or in large quantities, since they are difficult to digest.

image of fly agaric image of yellow fly agaric

Amanitas (Amanita spp.)

image of destroying angel
cross section diagram of amanitas

Amanitas are the reason why there are no old, bold mushroom hunters. Several members of this group contain amanitin, one of the deadliest poisons found in nature. One cap of a Destroying Angel (Amanita virosa) can kill a man

An amanita starts as an egg-shaped button which can resemble a small puffball. This breaks open as the mushroom grows. Fully developed amanitas are gilled mushrooms with parasol-shaped caps that may be white, yellow, red or brown. They also have the following characteristics:

  1. A saclike cup surrounding the base of the stem. This often is buried just beneath the soil surface and may not be obvious.
  2. A ring on the stem.
  3. White gills.
  4. A white spore print (see page 12).

Both the ring and the bulb may be destroyed by rain or other disturbance. For this reason, beginning mushroom hunters should avoid all parasol-shaped mushrooms with white gills.

Amanitas are usually found on the ground in woodlands in summer and fall, but be on the lookout for them whenever you hunt for mushrooms.

False Morels (Helvella and Gyromitra spp.)

image of helvella image of Gyromitra caroliniana
Helvella sp. Gyromitra caroliniana

False morels are difficult to treat in an article on edible and poisonous mushrooms, because they so clearly fit both categories.

On one hand, many people have enjoyed eating false morels for years and may even consider them a favorite wild mushroom. On the other, false morels have definitely caused serious illnesses and deaths in the United States.

The problem seems to involve the amount of a toxic chemical, called monomethyl hydrazine (MMH), present in these mushrooms. MMH causes diarrhea, vomiting and severe headaches, and occasionally it can be fatal. However, because of different cooking techniques and different individual sensitivities to MMH, false morels poison some people but leave others unaffected. In addition, false morels in some areas of the country contain more MMH than in other areas. All this makes these mushrooms a very doubtful group as far as edibility is concerned.

False morels have wrinkled, irregular caps that are brainlike or saddle-shaped. They may be black, gray, white, brown or reddish. (The "big red morel," Gyromitra caroliniana, common in Missouri, is a large false morel with a reddish cap.) Other names include elephant ears, Arkansas morels and brain mushrooms. Size 2" to 8" tall.

False morels differ from true morels in two obvious ways:

  1. The cap surface has lobes, folds, flaps or wrinkles, but it does not have pits and ridges like a true morel. You might say their caps bulge outward instead of being pitted inward.
  2. The bottom edge of the cap of a false morel hangs free around the stem, like a skirt. On true morels, the bottom edge of the cap is attached to the stem (see page 4).

False morels are found in spring, summer and fall, on the ground in woodlands.

Note: Because these mushrooms have definitely caused deaths, we cannot recommend that you eat them. If you nevertheless choose to do so, they should be thoroughly cooked in a well-ventilated room, since MMH is driven off by heat.

Little Brown Mushrooms (LBMs)

image of little brown mushrooms image of more little brown mushroom

Like the LGBs (little gray birds) of the birdwatchers, this is a catchall category. It includes all small to medium-sized, hard-to-identify brownish mushroom with spores of all colors-of which there are many hundreds.

Many LBMs are harmless, some are mildly poisonous or hallucinogenic, and a few are deadly. The innocent-looking little mushrooms of the genus Galerina are probably the most dangerous of the LBMs. They contain the same toxin as amanitas and have caused a number of deaths. Galerinas grow in clusters on wood and have brownish spores.

Because they are so difficult to identify, all LBMs should be avoided.

Little brown mushrooms are found in spring, summer and fall, in all habitats. Poisonous LBMS may grow on soil or wood and may appear in lawns, pastures or forests.

Jack-O'-Lantern (Omphalotus olearius)

image of jack o' lantern mushrooms

The bright-orange is well named. Not only is it pumpkin-colored and found in the fall- it also glows in the dark. Fresh specimens sometimes give off a faint greenish glow at night or in a darkened room.

These common mushrooms have caused many poisonings because they look, smell and even taste good. They cause mild to severe stomach upset but are not life-threatening to healthy adults.

Jack-O'-lanterns have a pleasant, fruity fragrance. They are sometimes mistaken for the edible chanterelle (see page 6), which is the same color and also has pleasant smell. Chanterelles, however, have flat-edged, interconnecting ridges or wrinkles instead of knifelike gills, and grow on the ground. Size 3" to 10" tall, cap 3" to 8" diameter.

These mushrooms are found in summer and fall, in large clusters at the base of trees, on stumps or on buried wood.

The jack-o'-lantern and green-spored lepiota are only two of a large number of mushrooms that can cause mild to severe (though not life-threatening) illness if eaten. To avoid poisoning from these mushrooms, be sure to follow the rules on page 8.

Green-spored Lepiota (Chlorophyllum molybdites)

green-spored Lepiota

These large, common mushrooms often appear in fairy rings on suburban lawns, and are frequently eaten by the lawn's owner-to his or her regret. They cause violent gastrointestinal upset.

The green-spored lepiota is parasol-shaped and has a cream or tan, scaly cap, a large ring on the stem and cream-colored gills which turn dingy green with age. As its name suggests, it is the only mushroom with a greenish spore print. Size 4" to 12" tall, 2" to 12" in diameter.

This mushroom is found in summer and fall, on the ground in lawns, pastures and meadows.

Copyright 1983 by the Conservation Commission of the State of Missouri reprinted from the Missouri Conservationist