The Mushroom Chronicles
Biology originally relegated all living things to two kingdoms; Plantae and Animalia. This was always problematic when classifying single celled organisms like the Euglena, which has the mobility of an animal and the chlorophyll of a plant. Fungi were considered members of the Plant Kingdom (the division Eumycota) even though they reproduced with spores and relied on chlorophyll-producing plants and other hydrocarbon sources of less repute such as manure and decayed rags for nutrition. In that dinosaurs were once considered reptiles, it is not at all surprising that the somewhat arbitrary nature of classification by taxonomy could yield anomalous results. With the increasing use of DNA testing to validate these relationships, the classification scheme originally devised by Carlolus Linnaeus will no doubt be subject to additional revisions
In 1969, R. H. Whittaker of Cornell University proposed five principle kingdoms: the original Plantae and Animalia with the addition of Fungi, Protista and Monera. Fungi included mushrooms, molds, mildews, yeasts, brackets and puffballs. Monera were the bacteria. The problem was that the fifth Kingdom, Protista, was for anything else that didn't fit one of the other four categories, such as amoebas, algae and slime molds, containing as many as 200,000 different species. To complicate matters, Carl Woese of the University of Illinois posited three domains: Bacteria, Archaea and Eukarya to take into account the unique genetics of bacteria and Harvard zoologist Ernst Mayr later suggested two empires: Prokaryota for simple bacterial entities and Eukaryota for the more complex organisms.. This debate rages on, but the key point is that fungi are not plants in any of these organizations. Fungi are fungi (the preferred pronunciation according to Webster's Dictionary is funj-eye but I have heard fung-eye, funj-ee and fung-ee with almost equal frequency)
Wild mushrooms are highly regarded by most cultures of the world as an important and delectable food source. Many fungi have the taste and texture of meat, attributable to their conversion of the plant nutrients into chitin, the same material that is used by insects for their exoskeletons. Appellations such as "Chicken of the Woods" and "Beefsteak Fungus" reflect this gastronomic verisimilitude. However, the British make a distinction between the edible field mushroom that is cultivated commercially, and all others which are called toadstools and are considered poisonous. The etymology of this term is curious, as it has nothing to do with the notion that toads may use the mushroom as a perch, as they are so frequently depicted in ceramic caricatures and children's' fantasies. Toadstool is a calque of sorts as it is of German origin, the word todesstuhl meaning death chair. Apparently the British took to the notion of a warty toad using the hated fungus as a throne. Americans have for the most part followed British traditions in their general apprehension of any mushroom not purchased in a proper commercial establishment.
The word mushroom itself is of dubious etymological origin. It derives from the French word moisseron which is in turn derived from mousse, the French word for moss. Perhaps this is due to the dark, dank mossy habitat where mushrooms thrive and moisseron became mushroom as a calque, using existing English words as antonyms for the French. Interestingly, the French word for mushroom is champignon from champs meaning fields (the Champs Elysee in Paris is the primary artery to the Arc du Triomphe. It means Elysian Fields, where fallen warriors live in perpetual bliss). Champignon is also the German word for mushroom, evidently taken directly from the French. And to really confuse things, the Latin word for mushroom is fungus, which in turn derives from the Greek spoggos, or sponge. Presumably, the Greeks, well known for sponge diving, thought that there was a resemblance between sponges and fungi, as both are fibrous, compartmentalized, and "spongy."
The mystifying, spontaneous emergence of mushrooms after rain is so notable that the very term "to mushroom" suggests explosive growth (both before and after the advent of the atomic bomb cloud of the same name). To understand why this occurs, it is necessary to delve into the recondite realm of spores, hyphae and mycelia. The evolutionary reason why mushrooms have caps is so that the spores which are located on small club-like structures called basidia attached to the gills under the cap remain dry. Thus, when the spores drop, the wind can then carry them to new habitats (wet spores would be too heavy). When a spore lands in an auspicious locale, it will start to grow, sending out an initial filament called a hypha that will branch repeatedly to create a fibrous mass called a mycelium.
The mycelium is the corpus of the fungus (what would we do without Greek?). It is as elusive to the casual naturalist as are the roots of a tree, as the hyphae are interwoven into the soil and detritus of the forest floor and thus virtually impossible to discern. Mycelia can grow to gargantuan proportions, limited only by the extent of a benign ecosystem. It is part of the accepted common folklore that the largest living thing in the world is a fungus that occupies some forty acres in Michigan. As I recall, the Soviets claimed during the Cold War that they had the world's largest fungus. They probably did and still do for that it now matters.
The mycelium that results from a single spore cannot create a mushroom. It takes two compatible hyphae growing from two compatible spores to do that. In this sense it is like the male and the female genders of most plants and animals. But with fungus, it is much more complicated, as there are a lot more pairing possibilities. There has been limited study in this area due to the difficulty in distinguishing different hyphae based on appearance. Understanding pair-wise behavior is dependent on a large number of tedious empirical observations. What testing has been done has shown more that 20,000 pairing combinations in some mushrooms. Each hypha brings one nucleus to the union, creating a cell with two nuclei, called a dikaryon. In this combined form, the mycelium grows, taking its nourishment from a variety of organic sources.
Mushrooms form from the dikaryon mycelium by coalescing into a more dense fibrous mass known as a primordium. The structure of the mushroom is established in embryonic form at this point with a distinct cap and stem, poised in the mycelium for the appropriate environmental stimulus, moisture. After a rain, water permeates the ground and the inchoate mushroom absorbs it, expanding rapidly with the preexisting structure now enlarged by the addition of the fluid. This is why mushrooms pop out of the ground overnight after a rain. The moisture trigger is also relevant to the propagation of the species, as the mushroom will open and release its spores when environmental conditions are likely to favor their successful incubation.
Fungi are among the most notable features of any woodland trail. The bright orange glow of Jack-O-Lantern mushrooms huddled at the base of a tree is as striking as the delicate structure of the Pink Lady's Slipper orchid. Their spontaneous appearance and ephemeral presence are like the wildflowers that enjoy universal adulation for their aesthetic qualities. But in spite of the esthetics of their geometric balance, mushrooms are maligned, subject to all manner of hyperbole about their toxicity and hallucinogenic nature. It is a matter of education, as fungi are of great importance to woodland ecology and to the economics of any agricultural enterprise. And that is the motivation for learning mycology and for transmitting that knowledge to others, the mushroom chronicles.
Medicinal Aspects of Fungi
Fungi do not make their own food. They rely on plants for sustenance, a characteristic they share with animals such as humans. Paul Stamets, in the book Mycomedicinals, offers that this is because "we shared a common ancestor more than 460 million years ago." When one considers that this was shortly after the Cambrian explosion when many life forms literally appeared overnight (from the geological perspective) and many early phyla were represented by a single organism, this is not as outlandish as it sounds. If it hasn't already, DNA evidence will undoubtedly demonstrate that this relationship can be genetically proven. The point of asserting this verisimilitude is that if fungi are similar to animals and have had to compete in a world governed by survival of the fittest, then those that have survived have done so by evolving the means to ward off predators. This would include things like microbes and viruses that also prey on animals. According to this logic, fungi should be a rich source of proven chemical combinations that ward off pathogens.
Homo sapiens have had to cope with insidious diseases throughout our shared history of some five million years. Drug therapy from naturally occurring substances was most assuredly a matter of serendipity. Through the ages, the lore of folk medicine was passed down through tribes and clans as the purview of the shamans of Asia and the medicine men of the Americas. It is well documented that Native Americans used plants for treatments of everything from menstrual cramps (spicebush) to sore throat (bloodroot). Their use of fungi is less well known, though there is evidence for the treatment of joint pain and congested organs. The only well documented use of fungi by Native Americans was as a styptic for the topical treatment of wounds. The manner in which it was applied attends to the caricature of the hardened warrior, as the fungi (typically a polypore like tinder fungus) was applied to the place affected and then set alight to burn the skin over the area of the wound. This practice was also common in China, perhaps an indication of the origins of the Native American peoples.
Fungi were also used by the early Europeans. In 1991, a Neolithic man was discovered in the Italian Alps when he emerged from ice in which he had been frozen since his death about 5,300 years ago. Named Oetzi for the Italian region in which he lived, he carried a thong with several pieces of birch polypore, Polyporus betulinus, threaded on it. Speculation is that he carried it as an antibiotic medicine, for it is now known that P. betulinus contains an antibiotic that acts on bacteria, resins that attack whipworms (an intestinal parasite), and agaric acid which is a carminative (causing gas to be expelled from the intestines). In that an autopsy revealed that Oetzi had worms, it is likely that this was his palliative. He also carried Fomes fomentarius, the tinder fungus; an essential for any alpine trekker in the winter. The tinder fungus, also called Amadou, was used both as a means to start a fire from a spark and as a way to transport an ember from one campfire to another. Remnants of fungal material fabricated in this manner have been found at Upper Paleolithic hominid sites dating back to 11,600 BCE. The tinder fungus was also an acknowledged curative, as the Greek Hippocrates identified it as a topical treatment for wounds over 4,000 years ago.
It is not clear why fungi never made the transition from evidently well known and practiced ancient herbalism to modern folk remedies to the extent that plants have. Historically, the identification of medicinals became a matter of the written record, necessary in order to identify the source, the manner of preparation, and the appropriate dosage for the given ailment. These listings of drugs are called pharmacopoeias; The Greek physician Dioscorides compiled one of the first pharmacopoeias called Materia Medica in 65 CE. In this book, one fungus, the "Agarikon Fungus" which most likely refers to the Fomitopsis officinalis, was listed as a panacea for ailments ranging from kidney disease to epilepsy. The Agarikon was a staple of pharmacology until at least the 18th Century, when it fell into obscurity. This is at least in part due to fact that Carolus Linnaeus, the father of taxonomy, gave the generic name Agaricus to a group of gilled mushrooms, of which the pedestrian, supermarket button mushroom (Agaricus bisporus) is a member. The United States Pharmacopoeia appeared in 1820 and the International Pharmacopoeia was established by the World Health Organization in 1951.
It should come as no surprise that mushrooms, or more properly fungi, have proven as well as potential medicinal attributes. In 1928, Sir Alexander Fleming discovered that the spread of the ubiquitous pus producing bacterium Staphylococcus aureus (it is gold or aurum in color) was arrested by a green mold. The organism that produced the substance was a species of Penicillium, so he named it penicillin. This marked the beginning of the antibiotic era. It wasn't until the advent of World War II that a way of producing large quantities of the new "miracle drug" was developed. The rest of the story is that Penicillium is the genus of about 250 species of blue or green mold fungi. Interestingly, the name Penicillium, and hence penicillin, has the same etymology as pencil, as the ends of the mold's conidiophores are tufted, like an artist's brush from which the modern pencil is derived. So the first miracle drug was a fungus.
Of the approximately 15,000 species of mushrooms, it is estimated that about five percent are utilized for medicinal purposes somewhere in the world. There are currently more than 250 species that are known to have therapeutic properties based on accepted clinical research. The primary medicinal agents in fungi are polysaccharides, which generally act against cancers and enhance the body's immune response. The healing and curative properties of fungi have been recognized and used for medicinal purposes in China and Japan for millennia. The earliest known pharmacopoeia in China (100 CE), Shen Noug Pen Ts'ao Jing, lists a number of mushrooms with medicinal applications. They have gained even greater import in the modern era as the fungi can in many cases be cultivated. The traditionalist medicine of the East has captured the imagination of the medical conservancy of the West. Acupuncture is one example. Fungi are and in all likelihood will continue to penetrate the pharmacopoeia of the general practitioner. Three examples will suffice to demonstrate the potential for modern medical treatments: The Trametes versicolor or Turkey Tail, the Ganoderma lucidum, or Hemlock Polypore, and the Lentinula edodes, or Shiitake.
Turkey Tail, known as Yun Zhi or "cloud mushroom" in China, is probably the most thoroughly studied of the medicinal fungi, as it is among the most widely used in East Asian medicines. In traditional Chinese herbalism, the fruit bodies are harvested and ground to a powder to make a tea that was used to reduce phlegm, treat pulmonary maladies, and promote a healthy liver. The Ming dynasty version of the pharmacopoeia provides that if the Yun Zhi is taken over a long period of time, "it will make one vigorous and live long." In the modern era, T. versicolor derived protein-bound polysaccharide (PSK) has been shown clinically to be effective against human cancers, particularly when used in combination with other agents. A 1982 study of cervical cancer patients given PSK with radiation found that the 3 year survival rate was 85 percent compared to 59 percent for those given radiation without PSK.
Ganoderma lucidum is known in China as Ling Zhi which means mushroom of immortality. The Latin name lucidum refers to the coruscating, varnish-like shine of the fruiting body when it first emerges from the side of a tree. It has been used in Chinese and Japanese folk medicine for at least four millennia in the treatment of age related maladies such as heart disease, hypertension, and chronic bronchitis so as to increase longevity. It was considered so powerful that it was used as a talisman to protect individuals and homes from evil spirits. In the last 30 years, it has been used in numerous human clinical studies to treat insomnia, duodenal ulcers, progressive muscular dystrophy, diabetes and Alzheimer's disease. It's efficacy in treating bronchitis was demonstrated in the 1970's when 75 percent of 2,000 patients showed marked improvement after two weeks of therapy.
Shiitake mushrooms are named for their association with the Asian shiia tree; the Latin species name edodes refers to their edibility. They grow wild in Japan and China but are not indigenous to North America, their widespread availability due to facile cultivation. They are second only to the Agaricus bisporus in commercial production. The two most important medicinal derivatives or the Shiitake are LEM (Lentinula edodes mycelium extract) and lentinan. Both chemicals have strong anti-tumor properties by enhancing the body's immune system rather than attacking the cancer directly. There have been innumerable clinical trials of the shiitake. For example, a controlled trial of 275 patients with advanced gastric cancer showed that those given lentinan with chemotherapy had statistically improved longevity and improved immune response. A group of Japanese women who ate 90 grams of shiitake mushrooms daily for one week had a 12 percent drop in serum cholesterol.
Fungus as pharmaceutical is a bit antithetical to the prevailing wisdom that wild mushrooms are deadly toadstools. Few stop to consider the source of penicillin, even as it established the idea of "miracle drug" that we have come to expect whenever we are sick. But tastes change as time proceeds. Instead of taking two aspirin and going to bed, perhaps in the future you may sit down to a meal of shiitakes with a turkey tail on the side.
Edible Fungi and Nutrition
Mushrooms or more generally fungi are neither plant nor animal; they do not synthesize their own food from the energy of the sun and they are not mobile. They are somewhat in between, though closer to animals according to their DNA. Some fungi are edible and some fungi are poisonous as is the case with wild plants; however, the toxicity of some wild plants does not militate against the consumption of those that are recognized as edible. Wild mushrooms, on the other hand, are generally and incongruously considered poisonous toadstools. And as if this were not enough, it is generally believed that fungi have no nutritional value. So why would anyone want to eat them? The first reason is gustatory; those who have tried wild fungi find them not only edible, but quite palatable. The second reason is nutritional; they are relatively high in proteins and minerals. The fact is that there are many identifiable wild fungi that merit consideration as a viable food alternative.
The consumption of edible fungi, though certainly of ancient origin, is not well documented in the historical record, though speculation is that trial and error during the "hunter-gatherer" epoch of human prehistory eventually led to the identification of those that were edible. In that there was cultural isolation during this era, different regions became either mycophilic or mycophobic, as postulated by ethnomycology theory. The mycophobia of Anglo-Saxons is reflected in the writings of the noted herbalist John Gerard in the 1597 Herball or Generall Historie of Plantes that "most of them do suffocate and strangle the eater." On the contrary, continental Europeans were and are mostly mycophilic. Vincent Marteka in Mushrooms Wild and Edible contends that mushrooms were a staple of the Native American diet, noting that the Iroquois "ranked the pleasure of eating wild mushrooms as virtually equal to that of eating meat."
Fungi are an excellent source the protein; commercially grown edible mushrooms have protein compositions that range from a high of 35 percent of dry weight (White or Button Mushroom Agaricus bisporus) to a low of 4 percent (Wood Ear Auricularia auricula). This compares to 25 percent for milk and 13 percent for wheat. Of equal importance to the amount of protein is the quality of the protein, as determined by the relative concentration of its twenty constituent amino acids. Eight of the twenty are considered essential for adults since they cannot be synthesized from other sources and must therefore be consumed directly from food. A good source of protein must have all of the eight essential amino acids or it must be part of a balanced diet that does; any deficiency in one results in a reduction in the synthesis of the other seven. The most popular commercial mushrooms contain all of these essential amino acids. In "Mushrooms," Chang and Miles rank foods according to their essential amino acids in relation to adult dietary requirements in a quantitative index on a scale of 0 to 100. Mushrooms (98) rank just below meat (100) and well above spinach (76).
Fungi have several other noteworthy nutritional attributes: they are rich in a number of important vitamins and minerals, they have low saturated fat, and they are low in calories. Fungi are the best non-animal source of vitamin D and have high levels of the vitamins niacin, thiamin (B1) and riboflavin (B2). Up to 70 per cent of the ash content of mushrooms consists of minerals, notably Potassium. One medium sized Portabella mushroom (a type of Agaricus bisporus) has more potassium than a banana and about twice as much as an 8 ounce serving of whole milk. Since one of the functions of fungi in mycorrhizal relationships with plants is the uptake of minerals, their high mineral content is not unexpected. The fat content of commercial mushrooms averages about 4 percent; of this, 72 percent is unsaturated fat that promotes HDL cholesterol as contrasted to animal fat that is saturated and abets LDL cholesterol. The most significant contribution to mushroom unsaturated fat is linolenic acid, one of the Omega 6 essential fatty acids. The caloric impact of mushroom consumption is nominal; 100 grams of mushrooms have about 25 calories.
Fungi have a cell structure that is comprised primarily of chitin just as plant cells are made primarily of cellulose. Chitin is better known as the material that makes up the exoskeletons of insects and crustaceans; the chitinous structure gives fungi the definitive texture and firmness distinct from vegetables and reminiscent of meat. Recent clinical studies have found that chitin consumption reduced body fat by 8 percent and cholesterol by 32 percent over a month long trial. It is hypothesized that this is because chitin forms an amino polysaccharide molecule that is highly polarized; the distribution of atoms results in high concentrations of positive and negative charge at separated points on the molecule. The charged regions bond with fats and bile to create a large indigestible polymer compound that is excreted from the body. The liver makes up for the loss of bile with new bile, reducing cholesterol in the process. The reduction in fats and cholesterol contributes to cardiac health and thus to longevity, a fact long recognized by the Chinese, who have consumed mushrooms as a matter of health rather than nutrition for millennia.
While nutritional values have only been determined for fungi that are sold commercially, the similarity in the protein and vitamin content of the different cultivated types suggests that wild fungi would have similar levels. There are several readily identifiable wild mushrooms that offer unique flavor in addition to the nutritional attributes delineated above. For example, Chicken-of-the-Woods or Sulfur Shelf (Laetiporus sulphureus) is aptly named, as it looks like, cooks like and tastes like chicken; its distinctive sulfur orange coloring is mnemonically represented in the species name sulphureus. Chanterelles are readily identified by their yellow horn-shaped fruiting bodies; the genus name Cantharellus is from the Greek kantharos which means drinking vessel, the flagons of history being made in the shape of a horn. Puffballs range in size from a few centimeters to half a meter in diameter; their smooth, white, rounded exterior facilitates identification. The genus name for large puffballs is Calvatia, from the Latin calva, meaning bald, also an appropriate mnemonic. Small puffballs are in the genus Lycoperdon, which translates somewhat loosely as "wolf passing wind," a reminder that a puffball must be harvested when young. Otherwise, the soft, creamy interior turns into spores that puff out a hole in the top, the result apparently calling to mind wolf wind.
It is a matter of record that the fast-food oriented American cultural diet has resulted in a host of weight and nutrition related maladies, among them diabetes and obesity. This is particularly troubling as it has now become apparent that children are increasingly at risk. Protein rich, low calorie, low fat and high fiber (chitin) fungi offer an attractive alternative. Popeye popularized spinach; perhaps "Morel Mary" could do the same for mushrooms.
Poisonous and Toxic Fungi
Among the hundreds of thousands of fungal species and the tens of thousands of those recognizable as gilled mushrooms, only about 100 would qualify as poisonous of which only about 10 are deadly. Nonetheless, poisonous mushrooms cast pallor on the consumption of fungi as food; the epithet toadstool elicits emotions that inappropriately and unfortunately associate the innocent mushroom with loathsome warty uncleanliness and therefore promotes mycophobia, the fear of fungi. The word toadstool itself has an etymology that is suggestive of Stygian origins; it is a calque word of German provenance. "Todesstuhl" means "death stool." One reason for mycophobia is identification since many of the deadly variants are similar in appearance to those that are edible; in many cases only an expert can tell them apart and even they can make mistakes. Another reason is indication; there are no sine qua non proofs of mushroom toxicity, poisonous mushrooms do not all blacken silver spoons and do not all taste bitter, popular nostrums aside.
History has impugned the mushroom as the source of the poison that has dispatched any number of notables, among them Claudius, the fourth Roman Emperor. The perpetrator is alleged to have been his fourth wife Agrippina who wanted her son Nero to succeed to the throne in lieu of Britannicus, the son of Claudius by his third wife Messalina (who had incidentally been put to death for her part in a previous assassination attempt). The death is recounted by the philosopher Seneca the Younger in December 54, only two months after the event occurred. According to his account, it happened quite quickly, the onset of illness and death being separated only by about an hour. The idea that mushrooms were the cause is perpetrated in later writings by Tacitus, Suetonius and Dio Cassius, the latter adding a description of Agrippina serving Claudius a plate of mushrooms. The mushroom death of Claudius is almost certainly apocryphal, as deadly mushrooms are relatively slow to act; those that act rapidly generally cause gastrointestinal distress that is rarely if ever fatal.
It is more likely the case that mushroom poisoning occurs as a result of volition, the decision to consume a mushroom of dubious identification resting with the victim. There have been occasions where arrogant decisiveness has overridden caution. The most notable case is that of Johann Schobert, a composer who was employed by the Prince of Conti in Paris in the latter half of the 17th Century. He wrote harpsichord concertos, opera and sonatas that purportedly served as the basis for some of the later work by Mozart, his contemporary. Schobert may have had a talent equal to that of Mozart; we shall never know, as he succumbed to mushroom poisoning. According to the historical account, he had gathered some mushrooms in Pré-Saint-Gervais near Paris with his family and proceeded to a restaurant to have the chef prepare them. When he was told that they were poisonous, he proceeded to a second restaurant with like result. Undeterred, he went home to Paris and made mushroom soup for dinner. He was joined in death by his wife, one of his children, and a friend, a doctor; fittingly, it was the doctor who had proffered the mushroom identification in the first place.
Mushroom poisoning is generally categorized into four types according to the symptoms that result. It is not practical to use the type of toxin as a basis for classification, since there is a paucity of knowledge about the nature and chemistry of fungal toxins in general; this is particularly true for fungi whose consumption may yield an unpleasant though not fatal result. In addition, for all practical purposes, the identification of the mushroom that caused the condition under evaluation is usually a matter of conjecture since the victim has succumbed to the condition after having eaten the evidence. The four types are protoplasmic poisons, neurotoxins, gastrointestinal irritants, and those that are toxic only in combination with other substances, notably alcohol.
The protoplasmic poisons are those that destroy cells that can lead to the failure of major organs. These are the deadly mushrooms. They are mostly of one genus, the Amanita, though there are some deadly species in the genera Lepiota and Galerina. The common names of the most prominent of the Amanitas are grim evidence of their virulence: the Death Cap (A. phalloides) and the Destroying Angel (A. virosa). The common names of the mushroom of the other genera are equally foreboding: Deadly Lepiota (L. josserandii) and Deadly Galerina (G. autumnalis). The so-called Amatoxin is called amanitin, reflecting the primary generic provenance - Amanita. It is a bicyclic octapeptide, which essentially means that it is comprised of ring-shaped structures with eight peptides, compounds of amino acids. Cell destruction is incident to the inhibition of RNA polymerase; the lack of messenger RNA precludes protein synthesis. Since the liver is one of the primary areas of protein synthesis in the body, it is particularly susceptible to amanitin.
Amanitin poisoning is characterized by a long latency period ranging from about 6 to 15 hours during which there are no adverse symptoms (it is for this reason that the rapid death of Claudius is not likely of mycological origin). This is followed by symptoms that are typical of a gastrointestinal irritant: abdominal pain, vomiting, diarrhea, and dehydration. A period of apparent recovery ensues, only to be followed about a day later by a gradual deterioration that includes a loss of strength, restlessness, and jaundice, the result of irreversible liver damage. The mortality rate ranges from about 30 to 90 percent according to the amount of toxin consumed and on the age and general health of the victim.
Treatment follows diagnosis which usually depends on an evaluation of the symptoms and a knowledge of dietary history. Although there is a commercially available radioimmunoassay (RIA) test kit available, it takes about two hours to get a result; since the timeliness of treatment following poisoning is crucial, it is rarely used for initial diagnosis. If immediate and determined remedial action is taken, the mortality rate is reduced to as low as 5 percent. Inserting a stomach pump to evacuate the bile from the duodenum is crucial to the treatment, as the impairment of the kidneys causes the amanitin to be recirculated to the liver where the bile carries to the intestines, a vicious cycle. There are two other types of protoplasmic poisons that are found in mushrooms: hydrazines and orellanines. Methylhydrazine is found in the False Morel, Gyromitra esculenta; its chemistry is very similar to rocket fuel. Orellanine is found in the Sorrel webcap mushroom, Cortinarius orellanus. The symptoms of both toxins are similar to but less severe than that of amanitin.
The neurotoxins, as the name suggests, cause neurological problems which can produce symptoms that range from convulsions, hallucinations, anxiety, depression, and coma to profuse sweating and spastic colon. The most well known of the mushrooms that produce neurotoxins is the Amanita muscaria, commonly known as the Fly Agaric for its traditional use as an effective pesticide against the insect. In Eurasia, it is bright red with white cottony patches on the cap, the epitome of the forest fungus. In North America, it is less conspicuous, typically with a yellow-orange hue. It has long been noted for its mind-altering properties, having been ostensibly used for this purpose by the Koryak tribesmen of the Kamchatka peninsula and by the Norse warriors known as the berserkers. The active ingredient is ibotenic acid and its derivative muscimol, the latter having about five times the potency of the former. Ibotenic acid is an excitatory amino acid; it simulates the effects of natural transmitters on neurons in the central nervous system. The symptoms occur about an hour after ingestion and are characterized by an initial period of dizziness that may succeed to drowsiness followed by intense activity, excitement, hallucinations, and delirium. The depression-mania sequence may repeat several times in cyclic fashion before abating in a few hours. It is almost never fatal unless large quantities are ingested, as may be the case with young children infatuated with its aesthetic appeal.
The Amanita muscaria also lends its name to the other major neurotoxin, muscarine; it was first discovered incident to investigations into the chemical constituency of its namesake mushroom. Muscarine is found at levels as much as one hundred times the level in the Fly Agaric in mushrooms from the genera Inocybe (e.g. I. geophylla, or White Fiber Head) and Clitocybe (e.g. C. dealbata, or Sweating Mushroom that often grows near the edible Fairy Ring Mushroom - Marasmius oreades - and is mistakenly consumed with it). The initial symptoms of muscarine poisoning are fluid related, manifest in increased perspiration, salivation, lacrimation and urination about 15 minutes after ingestion. Follow-on symptoms include vomiting and diarrhea that continue for up to 24 hours; the administration of the antidote atropine results in rapid remission and complete recovery. Though fatalities are rare, severe cases can cause cardiac and/or respiratory arrest.
The gastrointestinal irritants are the least defined and most widespread of the mushroom toxins. Their virulence ranges from mild, short-lived stomach discomfort to vomiting and diarrhea that can last for several days. Fatalities are very rare and are usually associated with desiccation of otherwise debilitated individuals, the very young or the very old. The specific toxins are generally unknown as the need for detailed chemical analysis is mitigated by the ubiquity of the potential causes and the by the non-fatal nature of the affliction. What is known is largely anecdotal, as few cases that are traced to mushroom poisoning are reported relative to the number that occur. This is exacerbated by the degree to which susceptibility to specific toxins varies from one individual to the next; some people become mildly ill after eating almost any wild mushroom. Therefore, the mushrooms that are unequivocally identified with gastrointestinal distress are those that are relatively widespread and which resemble an edible species; they are therefore mistakenly consumed with some regularity. Examples include the Jack-O-Lantern (Omphalotus illudens) that closely resembles the Chanterelle (Cantharellus cibarius) and the Green-spored Lepiota (Chlorophyllum molybdites) that closely resembles the Parasol Mushroom (Macrolepiota procera).
The most peculiar of the mushroom toxins is coprine, an amino acid produced by mushrooms of the genus Coprinus, notably C. atramenarius, the Alcohol Inky. Coprine is converted to cyclopropanone hydrate in the human body. This compound interferes with the breakdown of alcohol; because of its similarity to Antabuse in blocking the oxidation of alcohol in the acetaldehyde stage, it is sometimes called a disulfiram-like toxin. The symptoms are generally mild, consisting of flushing of the head and neck, tingling of the extremities, cardiovascular disturbances such as heart palpitations, headache and nausea. It is listed in field guides as edible, with caution; it has no adverse side effects if alcohol is not consumed for about three days.
Mushroom poisoning is a complex phenomenon, the complexity a result of the variation in fungi according to geography, genetics and local environmental fluctuations; the toxic content of individual mushroom species can vary from non-existent to virulent. A contributing and no less perplexing dilemma is the variability of susceptibility; the idiosyncratic response of different individuals who consume the same mushroom can range from gustatory pleasure to violent purging. The more extreme reactions do not tend to follow the typical vectors of age or general health of the victim, but seem rather to correlate to something syllogistic to an allergic reaction; this is thought to be attributable to certain constituents of wild mushrooms that are not found in other foods, such as the sugar trehalose.
The only safeguard against mushroom poisoning is knowledge and caution; the only other option is abstinence. In order to safely eat wild mushrooms, it is necessary to be able to recognize those which are edible. But this knowledge is not sufficient to prevent a potentially unpleasant, if not life-threatening event. One must also be able to recognize the poisonous species and have the knowledge of the subtleties of taxonomy that can lead to improper identification (as was the case the composer Schobert). Caution is necessary in consumption; only a small portion should be eaten on the first occasion of any individual's consumption of a wild mushroom. Since an adverse reaction is always possible, a smaller dose will yield a less harmful result. It is both safe and rewarding to eat wild mushrooms, if only a little care is exercised.
Mycorrhizal Fungi
During the Devonian Period some 400 million years ago, land plants first evolved from their aquatic origins. This required adaptations to the terrestrial environment. Although the plants produced their own photosynthetic nutrients from the sun they lacked the means to readily extract necessary mineral constituents from the land, as they had no true roots. The fungi had preceded them ashore by about 100 million years and had evolved to extract minerals by using root-like tendrils called hyphae to penetrate the primordial soil. However, as the fungi could not produce their own food, they needed carbon-based nutrients to absorb. It is hypothesized that this engendered a necessary relationship between the plants and the fungi to enabled them to live together on the land. This theory is bolstered by the observation that fossils from the Devonian have been discovered that clearly show the commingling of fungal hyphae and plant roots. The ability of plants and fungi to exploit diverse large habitats consequent to the breakup of Pangaea during the Mesozoic Era (225 to 65 million years ago) is considered to have been facilitated by the root-hypha association.
The mutualistic relationship that resulted was the mycorrhiza; the word originated in the late 19th Century when botanists discovered that plant roots, though infested with fungi, were not in any way damaged or dysfunctional. They described the condition quite simply as "fungus root" and gave it a name derived from the Greek words mykos for fungus and rhizon for root. The mycorrhiza is the mutualistic symbiosis of a plant and a fungus: both organisms benefit, and, in some cases, the association is obligatory if the populations of either are to increase. The fungal partner is called the mycobiont and the plant partner the phytobiont, either is referred to as mycorrhizal. In the current Holocene Epoch, it is estimated that over 90 percent of all plants are mycorrhizal.
The mutualistic mycorrhizal relationship between a plant and a fungus is in essence a sharing of the resources that are both necessary and sufficient for life. The plant supplies the fungus with hexose (having 6 carbon atoms) sugars. Since it is not "normal" for plants to exude nutrients to their surroundings, it is evident that one of the key mechanisms involved in the symbiosis is for the fungus to stimulate the permeability of the plant's cell membranes. The fungus converts the sugars into what are generally termed reserve materials, as they are used as a means to store energy. The primary energy repository is glycogen, which is a polymer of glucose molecules; it is sometimes called animal starch as it is one of the primary means of storing carbohydrates. It is in the form of insoluble granules that can constitute as much as 10 percent of the dry weight of the fungus. Mycorrhizal fungi also generally produce the disaccharide trehalose which can be converted directly back to glucose and polyhydric alcohols or polyols; where present, these constituents can comprise an additional 15 percent of the fungal dry weight. Some of the plant's nutrients are thus essentially stored in their associated "fungus roots," an energy reservoir with some intriguing implications that are manifest in the behavior of forest ecosystems.
The fungus supplies the plant with minerals from the soil, primarily phosphorous and nitrogen. Phosphorous is one of the key constituents of adenosine triphosphate (ATP), which, when hydrolyzed to adenosine diphosphate (ADP) is the primary mechanism of plant cell energy generation. One mole of hydrolyzed ATP yields about 10,000 calories (10kcal in common parlance) of energy as heat. Nitrogen is needed for nucleic acids and chitin, the primary fungal cell wall material; proteins are about 15 percent nitrogen. Phosphorous and nitrogen are accessed by the fungus through the creation of an extensive branching underground network of filamentous thread-like hyphae. The soil nutrients are scavenged by the hyphae, which are capable of storing soil minerals against a significant concentration gradient. Thus the fungus serves two functions; it searches out critical mineral nutrients over a wide geographic area; and it builds up a reservoir of the minerals for release to the plant when needed. It is this storage and release capability that makes the mycorrhizal relationship critical for plants growing in the middle latitudes which are subject to significant seasonal variations and their concomitant nutrient fluctuations; the fungi provide the surge capacity. A mycorrhizal fungus can store enough phosphorus to provide a reserve for the tree for about ten days.
There are seven types of mycorrhizas of which two predominate: endomychoriza and ectomycorrhiza. The prefixes accentuate the fundamental difference between them: "endo" is from the Greek endon, meaning within and "ecto" is from the Greek word ektos, meaning outside or external. In terms of mycorrhizal morphology, this means that endomycorrhizas penetrate within the root and ectomycorrhizas extend outside of the root. They are also distinctly different in their populations. Endomycorrhizas are much more common; there are estimated to be over 300,000 plant species in association with about 130 species of fungi. Ectomycorrhizas only involve about 2,000 mostly arboreal plant species; however, some 5,000 different fungi are involved.
Endomycorrhizas are frequently called vesicular-arbuscular mycorrhizas or VAM due to their structure. When a spore from an endomycorrhizal fungus germinates in the vicinity of a receptive plant root, it sends specialized hyphal tendrils that extend in between the root cells to form an arbuscule, meaning "little tree" to indicate its branching structure. Each arbuscule persists for a period that ranges from several days to about 2 weeks during which time it is believed to actively transfer phosphorus to the plant through its many branches. The fungus also forms vesicles, which are membranous cavities typically filled with lipids. In addition to the arbuscules and vesicles that are internal to the root, the fungus also produces an extensive network of hyphae that extend several inches away from the root. This "fungus-root" provides the plant with a vastly expanded volume of soil from which nutrients can be extracted.
Endomychorrhizal fungi are taxonomically distinct enough from all other fungi to warrant their own family; Glomaceae is in the order Glomales, of the Phylum Zygomycota that belongs to the Kingdom Eumycota (formerly Fungi). They are obligately biotopic, which means that they only survive in association with their mutualistic plant associate and that they cannot be grown in an axenic environment in the laboratory. They do not reproduce like the traditional fruiting mushrooms, but rather produce a large, thick skinned spores that typically form spore agglomerations called sporocarps that can be as large as one inch in diameter. All of these features are intended to promote long term survival of the fungus in a subterranean dormant stage, since they do not create a mushroom-like fruiting body to dispense millions of relatively evanescent airborne spores.
Endomycorrhizal plants are much more ubiquitous, numbering in the hundreds of thousands. It is easier to list the exceptions. Aside from the 2,000 woody plants that are ectomycorrhizal, the majority of those that do not associate with the fungi are what are generally characterized as weeds. That is, they are exploitive pioneer plants that germinate quickly in deficient soils with rapidly spreading, finely branched roots that can absorb adequate nutrients without assistance from VAM fungi. Examples include the cyperaceous sedge family and the juncaceous grasses and rushes. The association of fungi with plants across the broad spectrum of species is an additional insight into the nature of their co-evolution; the diversity is indicative many branches from an early common ancestor some 400 million years ago.
Ectomycorrhizas are not as ubiquitous as endomycorrhizas; however, they have a profound effect on the health of forests as they engage the fungi and the trees in an inter-related network of mutual association. The ectomycorrhizal fungus covers the outside of the roots of its associated photobiont with a mantle of hyphae that is called the Hartig net (Robert Hartig was a 19th-century German plant pathologist). The net consists of the hyphae that penetrate and surround the root, excreting hormones that promote root growth and suppress root hair growth; 30 percent of the root's volume is actually fungal. The overall effect is that the roots of an ectomycorrhizal plant are thicker and much more branched than the roots of a plant without a mycorrhizal fungus. What this means is the ectomycorrhizal plants have a much better root system that has a surge capacity to provide extra nutrients during periods of adversity and a extended reach to pull in nutrients from a greater volume.
The plants that enter into ectomycorrhizal relationships are limited in number but significant in size and importance. This includes all trees in the families of the Pinaceae (pines, firs, spruces, hemlocks and larches), the Fagaceae (oaks, beeches, and chestnuts), the Betulaceae (birches, alders and hophornbeams) and the Salicaceae (willows and poplars) in addition to most myrtles and legumes. In general, the roughly 2,000 plant species from 130 genera in 43 families that enter into ectomycorrhizal relationships with fungi are perennial and woody trees and shrubs. While some of ectomycorrhizal trees are obligately mycotrophic like the pines, most are facultatively mycotrophic, they can survive without the fungi but assume a mycorrhizal relationship in response to stressful environmental conditions. It is this association that promotes the long-term health of the trees; it is these trees that make up the dense stands of trees that comprise the boreal forests and play a significant role in the ecologically balanced habitats. Fungi provide the anastomosis of the root systems, the interconnections and branches that allow the pure stands of trees to predominate. Laboratory and field experiments have demonstrated the trees share carbon resources through their mycorrhizal root systems.
The fungi that enter into ectomycorrhizal relationships extend across a broad range of species that include 45 genera gilled Basidiomycetes and 18 genera of the Ascomycetes. These include many from the ubiquitous agaric genera such as Russula, Lactarius, Cortinarius and Amanita in addition to the chanterelles and the boletes. Some ascomycetes are also mycorrhizal; the truffles are all thought to rely on tree roots for their sustaining nutrients. Most of the fungi can associate with a number of trees, though there is a preferential relationship between some mushrooms and certain host trees; chanterelles prefer oaks and confers while yellow morels prefer dead elm trees and yellow poplars. Mycorrhizal trees can have many fungal partners; the Douglas fir, among the most studied of the pines due to its importance in the timber industry, is thought to be able to form ectomycorrhizas with over 2,000 different fungi.
Of the other five types of mycorrhizas, three are of some interest, the ericaceous, the monotropoid and orchidaceous mycorrhizas. Ericaceous mycorrhizas are with plants of the family Ericaceae, which includes the heathers, rhododendrons and azaleas. That these plants are able to thrive in marginal acidic soil at high altitudes and colder latitudes is due to the exploitation of these habitats by their associated fungi. The colorless, flowering plants of the genus Monotropa such as the Indian Pipe have an unusual life cycle. As they are achlorophyllus, they cannot make their own food. They get it from a fungus via monotropoid mycorrhizal relationship, though no one knows if the plant provides anything to the fungus in return. The key to this unusual relationship is that it is tripartite; the fungus is in an ectomycorrhizal relationship with a nearby tree. The Monotropa thus gets its nutrients from the fungus which in turn gets it from the tree.
Orchidaceous mycorrhizas are necessary for orchids to survive; they are obligately mycorrhizal. The unusual thing about the relationship is that the fungus provides carbon to the orchid, carbon that it has extracted saprophytically from the soil. So far as is known, the fungus gets nothing in return; like the monotropoid mycorrhiza, it is not a mutualistic association. This is of prime importance when the orchid is a seedling, as the seeds of the orchid are very small and have inadequate resources for development. Without the colonizing fungi, the orchid perishes. The provisioning of the orchid plant with carbon by the fungus can be a long term proposition, as some orchids do not produce their first chlorophyll bearing leaf for over ten years. That this is a successful relationship is manifest in the ubiquity of orchids, there are tens of thousands of species.
Fungi are fundamental to the health of natural ecosystems. The mycorrhizal relationship between the food absorbing species of the Kingdom Eumycota and the food producing species of the Kingdom Plantae is critical to the survival of many of the species of both. The hyphae of mycorrhizal fungi permeate the soil and form extensive networks through which nutrients are shared among the associative trees, a relationship that has been facetiously called the "wood wide web." Some carry this even further; Paul Stamets in "Mycelium Running" asserts that the mycelia is "the neurological network of nature." Perhaps not, but it is abundantly clear that fungi are key to the restoration of healthy ecosystems damaged by human activities associated with timber and mining resource extraction. … To say nothing of the potential gains that could be made in agriculture to feed a hungry planet.
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