II. FUNGI AS SAPROBES                                                TOP

A. Beneficial Activities of Saprobic Fungi

6. Non-cultivated Edible Fleshy Fungi

6. Non-cultivated Edible Mushrooms & Allies:

Prior to WWII, Britishers were highly mycophobic and as a result many of the Scotch-Irish and Anglos that settled the Southeastern US had a great aversion to mushrooms. Florida, with its large number of ethnic groups, differs in that they have a keen interest in wild mushrooms. Each year there are more and more mushrooms and other fleshy fungi that are being cultivated for food (Fig. 7-1). 

Fig. 7-1. A variety of different mushrooms.

Yet, there are a far greater number of wild edible mushrooms and related fleshy fungi that have not been subject to cultivation. Later in the course we will discuss mycorrhizal fungi, i.e. those that grow in a symbiotic relations with higher plants. Although these are not saprobes, it seems appropriate to discuss them with other edible mushrooms.  Thus far, mycorrhizal fungi are difficult to grow in pure culture and have not been induced to form sporocarps in the absence of their higher plant partners. Several mycorrhizal fungi are highly prized for food and are actively sought during the rainy season by mycophagists (those who collect mushrooms for food). Picking wild mushrooms for food has been a long tradition among continental European and Asian cultures. Many of these ethnic groups maintained this tradition after settling in North America. Hunting for edible wild mushrooms became an exciting adventure for the “back to nature” enthusiasts during the past two decades. The general interest in wild mushrooms has grown to the point that there are commercial pickers and buyers springing up throughout North America. Collecting wild mushrooms for a profit has become a problem in the U.S. and Europe. Populations of some of the favorable edible species have dwindled over the years, large numbers of hunters have resulted in site depredation, and aggressive buyers have been a problem to law enforcement.

 There are many “old wives tales” that have been used in attempts to determine edible and poisonous mushrooms. Many people feel that all wild mushrooms are  toadstools and therefore poisonous. This term probable came from the German tode, which means death, and stuhl, which means stool. In many areas, highly toxic species of Amanita are referred to as death cups or toadstools. To many people, mushrooms are those you buy in the supermarket. Mushrooms and toadstools are “one and the same.” Unfortunately, mushrooms do not come with a “goodhousekeeping” label (Fig. 7-2), or a warning label, like cigarettes, caution, these may be injurious to your health. 

Fig. 7-2. Unfortunately mushrooms do not have 'Goodhousekeeping' seals of approval.

There is only one sure way to determine if a mushroom is toxic to you, i. e. like redeye, “take a bite” (Fig. 7-3). 

Fig. 7-3. One can experience severe consequences by simply taking a bite.

Every culture has had their favorite wild mushrooms, of which the following are most common:

a. Armillaria.

The Tricholomataceae is a large and confusing family of mushrooms with genera growing in various types of habitats. Several groups have edible species. These include: Armillaria which contains the honey agaric, A. mellea (Fig. 7-4) and the mushroom root rot fungus A. tabescens.

Fig. 7-4. The honey agaric, Armillaria mellea.

Both are straw colored and grow in clusters on decaying wood, or more often around the base of trees with heart rot or root rot.  A. tabescens is more common in the months of autumn, whereas, A. mellea occurs commonly in the early spring months. Armillaria ponderosa, the American matsutake mushroom, commonly called the pine mushroom, is one of the most highly prized mushrooms in the Pacific Northwest. Top grade collections sell for close to $100/lb., and in some years close to $10 million are received from matsutake sales. In Florida, there occurs Lentinula boryana (Fig. 7-5), a sister species to the common  shiitake mushroom. 

Fig. 7-5. The Florida shiitake, Lentinula boryana.

In fact, I call it the Florida shiitake. Since it is a native of the U.S., it may perhaps be more easily produced than the real shiitake.

b. Lactarius and Russula.

The Russulaceae has two common and very abundant genera, Russula and Lactarius. They are short, broad mushrooms without an annulus and have distinctly ornamented spores that turn blue in iodine. Species of  Lactarius (Fig. 7-6) differ from Russula (Fig. 7-7) by the presence of latex ducts that exude milk when broken, i.e. lactates; hence the name Lactarius. 

Fig. 7-6. Lactarius corrugis, a common edible species.

Fig. 7-7. Russula emetica, tasty for tortoises, but bad for man.

Several species of Lactarius, however, are highly sought after for food. Some have a nutty taste and crunchy texture. One should be able to use a good field guide to mushrooms and to eliminate good ones from bad ones. Because of their poor texture, few species of Russula are recommended for food.

c. Cantharellus.  

This is a genus of mushroom-like polypores that are mostly bright pumpkin-yellow in color, trumpet-shaped, and with broad folded gill areas (Fig. 7-8). 

Fig. 7-8. Cantharellus cibarius, highly prized for food worldwide. 

They have a distinct taste, nicely flavoring numerous dishes, and are avidly collected by mushroom hunters. There are several species found throughout the United States.  It’s sister genus, Craterellus, is purplish-brown in color, and the spore surface is normally less folded then in Cantharellus. They are also included among our choice edible mushrooms.

d. Boletes.

The Boletales or “boletes” are poroid mushrooms (Fig. 7-9), i.e. they have pores beneath the cap instead of gills. 

Fig. 7-9. Boletus edulis; many prize it over other mushrooms.

There are close to 25 genera in the Boletales; most are choice edible species with a delicious taste and texture.  One of the largest groups is Boletus with many edible species. A few species, however, can cause severe intestinal irritation, but they can be avoided if one discards species that turn blue on bruising or those in which the mouths of the tubes are apple-red. Many of the species of Tylopilus are inedible because of their bitter taste.  Most of the species of  Suillus and Strobilomyces are edible and delicious.

e. Pluteus and Volvariella. 

The Plutaceae contains pink-spored mushrooms with choice, edible species. We have already discussed Volvariella, the paddy straw mushroom, as one of the species that is cultivated extensively. A sister genus that is widespread throughout the U.S. on sawdust, decaying logs, and plant debris is the  deer mushroom, Pluteus cervinus (Fig. 7-10). 

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Fig. 7-10. Pluteus cervinus, the common deer mushroom.

It is widely sought after by mushroom hunters and can be distinguished from Volvariella by the lack of a volva.

f. Lepiota.

Lepiotaceae, the common  parasol mushrooms, are most common on lawns, pastures, and golf courses. Species of Lepiota  have a long reputation of being choice edible mushrooms. They have free gills, white spores, and a distinct annulus or ring on the stalk. The green-gilled genus Chlorophyllum that forms fairy rings in lawns throughout the southeastern U.S. is easily confused with Lepiota. Chlorophyllum has green spores and contains toxic metabolites. Some people have eaten it without problems; most, however, develop severe nausea and gastrointestinal irritation. Because of its size and abundance, and its confusion with  Lepiota, it causes more mushroom poisoning than any other North American mushroom.

g. Coprinus.

The Coprinaceae is a black-spored family of mushrooms that contains the interesting  inky cap mushrooms we call Coprinus. When young, species of Coprinus are firm and fleshy, and emit delicious flavors to foods. They are readily noted in the field where they grow on decaying grass, compost piles, sawdust, and other cellulosic substrates. All species go through an autodigestion at maturity in which the cap forms black spores that become a soupy black glob (Fig. 7-11; Fig. 7-12).  

Fig. 7-11. Coprinus in the early morning.

Fig. 7-12. Coprinus becoming 'inky -capped' by noon.

Unfortunately, species of Coprinus contain a cyclopropane-like compound called coprine that when released by alcohol produces all kinds of weird symptoms in man. The symptoms are much like the effect of alcohol on alcoholics who are on antabuse tablets! So, if you eat Coprinus, avoid alcohol for several hours...and visa versa.

h. Bracket fungi/polypores.  

Some of the wood-rotting bracket fungi, such as Laetiporus sulphureus (Fig. 7-13), the sulphur polypore, are tender, succulent and very tasty. 

Fig. 7-13. Laetiporus sulphureus , the common sulphur polypore.

Those who have tried both, say that the sulphur polypore has the taste and texture much like the famous truffles. A somewhat related bracket fungus is Fistulina hepatica (Fig. 7-14), the beefsteak fungus, which supposedly tenderizes and adds flavor to meat.

Fig. 7-14. Fistulina hepatica, the beefsteak fungus.

i. Morels.

Morels belong to a group of sponge-like “mushrooms” whose Latin name is Morchella (Fig. 7-15).  

Fig. 7-15. Morchella esculenta, a mushroom look-alike; some would kill for this choice edible ascomycete.

They are not true mushrooms but belong to the Ascomycota, you remember, those that produce their spores in sacs. They are a group of discomycetes (cup-fungi) in which the apothecium is stalked and the spore-bearing area (hymenium) has gone wild, thus the spongy configuration. Morels are highly prized for food around the world. In India they are referred to as Khombi and are given center stage in special dishes. Morels appear during a short window of time in the spring whenever new tree leaves are emerging and soil temperatures rise. They are found only in certain habitats, i.e. around decaying elms, old apple orchards, etc., and these sites are held secret by morel pickers because next year they go back at the same time and same place and likely find them again. These factors, coupled with the delicious taste and texture, make them expensive when you are able to find them for sale. In certain Midwestern states, there are annual contests with nice prizes for the individual who finds the most morels. Close to 1,300,000 lbs are collected and sold each year in the Pacific Northwest; and in some years demanding a price of $10/lb. Until 1989, these fungi had escaped cultivation. It had been known for almost a century that morels would form sclerotia in culture, but it was the discovery by Ower et al. (U.S. Patent 4,594,809) that from overwintering sclerotia, the sporebodies of Morchella are formed. Nutritional and environmental studies have now enabled individuals to be able to grow morels under artificial conditions. Terry Farms at Zellwood, Florida, a farm that specializes in the production of the “button mushroom,” opened a $6 million morel farm near Auburn University in Alabama in 1998.

j. Truffles. 

“Man has measured the skies, explored its depths, invented all kinds of transportation and communication devices, extended our lifespan with miraculous drugs and technology, but he still cannot make a  truffle grow.” (anonymous). This is no longer true.  Truffles have historically been considered the most highly prized, edible fungi and have demanded prices up to $600/lb. throughout parts of the world where they are found. Truffle sales reach close to $25 million annually and individual truffle hunters can make up to $18,000 during the brief truffle season. Truffles are actually not mushrooms, but underground Ascomycetes related to large cup-fungi like Peziza. Species of Tuber (Fig. 7-16) have long been prized for food throughout European countries and because of their underground growth, like potato tubers, and their association with only certain tree species, they are not easy to find. 

Fig. 7-16. Tuber borchii, one of the edible species of truffles.

Man, however, has learned that dogs and hogs have a keen sense of smell and have taught these animals to hunt truffles for them (Fig. 7-17)! 

Fig. 7-17. Truffle hunting with hog and dog.

Being such a pricey delicacy, truffling has become extremely competitive. In 1997, there were 27 well-trained truffle dogs poisoned in Northern Italy (Gainesville Sun, Nov. 30, 1997), probably by competitive truffle hunters.

Species of Termania and Terfezia are collected extensively and sold in the markets in arid countries of the Middle East. Although scientists have obtained pure cultures of various truffles over the years, no one has been successful in inducing a truffle under artificial conditions. While it has been known for more than a century that truffles were mycorrhizal on various trees such as oak, beech, birch, hazels, and a few others, it was not until the early 1960s that foresters and mycorrhizal workers understood that for many of these trees, the presence of mycorrhizae was absolutely essential for the normal growth of these hosts.  By the same token, we have come to realize that the mycorrhizal fungi must also be associated with a host before it will develop a sporocarp. This is the situation with species of  Tuber and other truffles. With mycorrhizal technology, many attempts are being made both in Europe and the U.S. to aseptically grow beech, hazel, oaks, filberts, or other suitable partners and inoculate their root systems with a particular truffle. After determining that a mycorrhizal partnership has been established in the greenhouse, inoculated seedlings are planted as orchards and the growers anxiously wait for 5-6 years to get their first crops of truffles. With the decline of truffles in Europe, because of their forest practices, truffles have become increasingly scarce and more costly. Truffle orchards should make truffles more abundant and less costly on the market.

k. Corn Smut. 

Because of its food value, it seems appropriate to discuss an interesting edible plant parasite. Several varieties of corn, especially sweet corn, become infected each year in most areas where corn is grown by a smut fungus Ustilago maydis. As the corn is in silk, the young grains will become infected with this fungus, swell to golf-ball size, and eventually turn black because of the dark smut spores inside the infected kernels. These swollen infected kernels are picked while they are white and firm and are used for food (Fig. 7-18). It is called cuitlacoche in Mexico and is recognized as a delicacy and is served in elegant restaurants.  

Fig. 7-18. Canned cuitlacoche available for purchase.