Starfish fungus (Aseroe rubra) on the Hawaiian Island of Molokai. The dark, slimy spore mass has a fetid odor and attracts flies.

Two additional stinkhorns include the octopus stinkhorn (Clathrus archeri) with 5-8 slender arms emerging from a basal "egg" stage, and "stinking squid" (Pseudocolus fusiformis) with 3-5 tapering arms resembling tentacles.

The bright red fungus (left) is the vivid "scarlet cup fungus" (Sarcoscypha coccinea), a striking fungus found occasionally in moist forests of the Pacific northwest. There may be at least 200,000 species of fungi still waiting to be described.

Most fungi are heterotrophic (unable to carry on photosynthesis) and must rely on organic nutrients such as cellulose and proteins from their host or substrate. They secrete powerful digestive enzymes that break down live or dead materials into sugars and amino acids that can be absorbed through the fungus cell walls. At least 20,000 species of fungi are "lichenized" and contain symbiotic photosynthetic algal cells or cyanobacteria that form a remarkable "marriage" that has enabled both partners to survive in inhospitable places where neither symbiont could survive by itself. Lichenization has undoubtedly occurred more than once during the geologic past, and like human marriages, the relationship ranges from mutualism to controlled parasitism. The algal partner (photobiont) provides its fungal host with energy-rich carbohydrates, while the fungus (mycobiont) forms a protective body for the delicate algal cells that can withstand extremes in temperature, wind and desiccation.

Fungal spores germinate and grow into slender tubular threads called hyphae which may be septate or nonseptate (i.e. without cross-walls) depending on the species. A mass of intertwined hyphae is collectively referred to as a mycelium. The body of fungi and lichens, which is composed of mycelia, is called a thallus. Under optimal conditions the hyphae often grow very rapidly, and it has been estimated that if all the hyphae produced in a day by a single soil fungus were laid end to end, they could extend for nearly a mile. Many species of soil fungi have their hyphae intimately attached to the roots of forest trees in a symbiotic association called mycorrhizae ("fungus- roots"). In mutualistic mycorrhizal associations, the roots furnish the fungus with sugars and amino acids, while the fungus facilitates in the absorption of water and mineral nutrients by the tree.

The mycelium of some forest fungi can extend enormous distances. A single individual of Armillaria bulbosa has been discovered that permeates more than 30 acres of forest soil in northern Michigan and may be one of the world's largest living organisms. Some scientists speculate that it was spawned by a single spore thousands of years ago. Another Armillaria in Washington was recently found to consist of a subterranean mycelial network with erect, above-ground mushrooms covering more than a thousand acres of forest soil. These fungal monstrosities are rivaled in total size and mass by a 106 acre, 6,000 ton stand of genetically identical quaking aspen in the Rocky Mountains. The aspen clone is connected by a common root system, and has literally climbed over mountains and across meadows. Any discussion of massive clonal colonies should also include the conjoined polyps of coral reefs. However, the question still remains: Do these clonal colonies qualify as a single individual, as in the 1200 ton General Sherman tree of California's Sequoia National Park?

Although they are listed as fungi in many biology textbooks, some biologists now place the remarkable slime molds in the large and diverse Kingdom Protista, along with water molds, unicellular and multicellular algae, and the diverse protozoans. With colorful, multinucleate plasmodial bodies, they are able to slowly creep along the rain-soaked forest floor in an amoeboid fashion. The old sci-fi movie "The Blob" was undoubtedly created in the image of these bizarre organisms. There are also a number of fleshy, non-green (without chlorophyll) forest-dwelling wildflowers that have truly evolved a fungal mode of life. Termed "mycotrophic" or fungus-nutrition, these remarkable wildflowers are attached to mycorrhizal soil fungi which in tern are attached to the roots of trees. Organic nutrients produced by the trees are translocated into the wildflowers via the symbiotic soil fungi. Some spectacular examples of these white, fleshy, fungus-like wildflowers are Monotropa (Indian Pipe), Pleuricospora and Pityopus. In fact, without carefully examining Pityopus in the dark forest understory, you would never believe that it is a flowering plant and not a fungus.

The life cycle of a typical mushroom is very complex. At certain times of the year, opposite mating strains (+ and - strains) of subterranean, septate, haploid (n) mycelia fuse together producing dikaryotic (n + n) septate mycelia with two kinds of nuclei (+ and -) in each cell. These (n + n) mycelia grow into visible, above-ground, spore-bearing reproductive structures (called fruiting bodies) that we recognize as puffballs, morels, mushrooms and shelf fungi. Prior to the formation of spores there is a fusion of the (+ and -) nuclei within special cells to form diploid (2n) zygotes which undergo meiosis to form the haploid spores. Based upon the type of spores in these fruiting bodies, fungi are placed into different classes such as the Ascomycetes and Basidiomycetes. The number of spores produced by these fruiting bodies (technically referred to as ascocarps or basidiocarps) can be astronomical. It has been estimated that a single basketball-sized puffball (Calvatia gigantea) could produce enough spores in just two generations to theoretically produce a total volume of puffballs seven times the size of the planet earth.

Dead Man's Fingers Xylaria polymorpha Another fungus named after human anatomy is called "dead man's fingers." The fruiting body (sporocarp) is divided into fingerlike "digits" that are often fused together at the base resembling a human hand. Unlike "dead man's foot," a basidiomycete (division Basidiomycota) related to puffballs, this species belongs to the division Ascomycota, order Xylariales. It is fairly common in forested and woodland areas of eastern North America.

Some fungi have very complicated life cycles, spending part of their life on one host, and then spreading by spores to another host. In fact, the presence of fungal mycelia within the tissue of plants often causes the host to produce abnormal-appearing growths called "galls." You have probably seen swollen, deformed peach leaves caused by the fungus Taphrina deformans. The familiar reddish balls called "cedar apples" that decorate many species of junipers are galls caused by rust fungi of the genus Gymnosporangium. In spring the galls are covered with radiating gelatinous spikes bearing thousands of teleutospores. These spores must infect nearby apple or crabapple trees in order to complete their life cycle. It is best to plant apples away from junipers, unless you like cedar apple galls on your junipers. The most extraordinary galls are caused by rust fungi of the genus Puccinia. Certain Puccinia species attack rockcresses (Arabis) in the Rocky Mountains, causing these wildflowers to produce flowerlike, leafy stalks called "pseudoflowers." The bright rosettes of showy leaves are covered with droplets of fragrant nectar and fungal reproductive cells called spermatia. Attracted by the sweet, honeydew secretion, insects transfer male and female spermatia to other pseudoflowers, thus enabling sexual reproduction of the fungus.

As decomposers, fungi are essential because, along with bacteria, they recycle vital elements, such as nitrogen and phosphorus, back to the ecosystem. Although the beneficial effects of fungi far outweigh their negative aspects, there are some destructive and disease-causing species. Fungi can attack the cellulose acetate of color transparencies and film, contaminate food products such as breads and canned goods, and even etch glass lenses as they grow on minute quantities of organic compounds. So named because their sexual cycle has not been clearly observed, the imperfect fungi (Class Deuteromycetes) include several disease-causing species of humans, including aspergillosis of the respiratory tract, athlete's foot, ringworm, unsightly toenails, and the very serious "valley fever" of the southwestern United States.

Economically valuable fungi include the strains of yeast responsible for the fermentation of grains and grapes in the beer and wine industries, and yeast responsible for the rise of baked breads; prized (and expensive) edible truffles, chanterelles, boletes and other delicious mushrooms; the ripening of Camembert, Roquefort and other blue cheeses; the source of the valuable antibiotic penicillin (from the bread and fruit mold Penicillium); and the source of ergotomine (from ergot fungus), a muscle and blood vessel and constrictor that relieves the horrible pain of migraines, stimulates uterine contraction during childbirth and prevents hemorrhaging.

Of all the edible fungi, truffles (Tuber spp.) are perhaps the most fascinating. Truffles are the fruiting bodies (ascocarps) of mycorrhizal ascomycetous fungi. Unlike other common forest mushrooms, truffles are subterranean and resemble small pebbles or clods of dirt beneath the soil. Depending on the species, they may be 1-2 cm across (e.g. Tuber gibbosum of the Pacific Northwest). They are typically harvested with a garden rake if you know of a reliable site; however, ingenious humans have discovered that certain mammals, including pigs and dogs, can sniff out these delicious fungi. Although pigs and dogs are the most accomplished (and popular) truffle hunters, these subterranean delicacies are also sniffed out by goats in Sardinia and bear cubs in Russia. Pigs and dogs can detect truffles from as far away as 50 yards, and there is even a case of a dog jumping over a hedge and running across a field to find a choice truffle under a beech tree 100 yards away. Since the fabled truffles of France and Italy retail for more than $500 a pound, a good swine or canine truffle sniffer is a valuable asset.

Some truffles emit the odor of certain mammalian steroids, including androstenol (androst-16-en-3-ol), a chemical that occurs in the black truffle Tuber melanosporum and in the testicles of swine. In fact, it is found in the saliva and breathe of rutting boars, where it serves as a pheromone to overcome the sexual inhibitions of young female pigs. This probably explains the natural lust and talent sows have for truffle hunting. The same substance is found in the underarm perspiration of men and in urine of women, and truffles have been used for an aphrodisiac. The sexual role of truffles in humans has not been clearly established, however, men rating photographs of normally dressed women for sexual attractiveness generally give higher marks while sniffing androstenol. This chemical is already being added to certain cosmetics designed to attract potential mating partners. Unlike other above-ground mushrooms, truffle spores do not depend on wind dispersal. Instead they are spread by various truffle-eating animals, including rodents, deer, pigs, insects and slugs. The spores pass through the digestive tract of these animals unscathed.

Compare the following structural formula of androstenol with the male and female sex hormones testosterone and progesterone. All steroids have the same fundamental structure of four (tetracyclic) carbon rings called the steroid backbone or steroid nucleus. The addition of different chemical groups at different places on this backbone leads to the formation of many different steroidal compounds, including the sex hormones, the anti-inflammatory steroid cortisone, and the cardiac steroids digoxin and digitoxin. The important animal steroid, cholesterol, also has this tetracyclic backbone structure. In fact, cholesterol is a vital steroid in our body because it is the precursor for other human steroids.

In the true spirit of convergent evolution, there are also false truffles (including Hymenogaster spp.) in the fungal class Basidiomycetes that are practically indistinguishable from true truffles until you microscopically examine their spores. The California red-backed vole dines almost exclusively on truffles and its range correlates nicely with the coastal fog belt where truffles and false truffles occur year round.

Although most fungi are not deadly, there are some species that contain dangerous neurotoxins. Generally, poisonous mushrooms are characterized by the presence of white spores, a cuplike volva at the base of the stalk, a ring or annulus on the stalk, and remnants of the universal veil on the umbrellalike cap. Because some of these traits are evanescent (quickly fading from sight), they are not always reliable depending on the age and condition of the fungus. Placing a silver coin in a pan of cooking mushrooms to see if it turns black is not a reliable method of testing poisonous mushrooms. Unless you understand fungal terminology and know how to use a good taxonomic key (such as Mushrooms Demystified by David Arora, 1986), I usually do not encourage self indulgence on wild mushrooms.

The beautiful, red, fly agaric mushroom (Amanita muscaria) is unmistakable with its bright red cap covered with white scales. It contains the toxic alkaloid, muscimole, which is derived from ibotenic acid--an amino acid. In Europe these mushrooms were reportedly left in open dishes to kill flies; however, according to some authorities, flies are merely stunned or stupefied by the toxin, and may even regain control and fly away.

Although the fly agaric is poisonous to humans, there are other species of Amanita that are much more dangerous and are potentially lethal if ingested. Some of the dangerously poisonous species of Amanita are death cap (A. phalloides), death angel (A. ocreata), and panther amanita (A. pantherina). Fortunately these latter deadly poisonous species are not bright red and are seldom confused with A. muscaria; however, they may be confused with other edible mushrooms by inexperienced gourmets.

In sublethal doses, the fly agaric mushroom (Amanita muscaria) may produce visions and delirium, and it is perhaps one of the oldest known hallucinogens. Recent studies suggest that this mushroom was the mysterious God-narcotic "Divine Soma" of ancient India. Thousands of years ago, Aryan conquerors who swept across India, worshiped soma, drinking it in religious ceremonies. Many hymns in the Indian Rig-Veda are devoted to soma and describe the mushroom and its effects. There are reports of Siberian tribesmen who ingested the mushroom to get intoxicated. Since the active chemical passes through the body relatively unaltered, others would drink the urine from these men to get high. This way a few mushrooms could inebriate many people relatively safely and efficiently. Lapland shamans eat fly agaric mushrooms for enlightenment and some authors think this may have given rise to the flying reindeer and the red- and white-costumed Santa Claus legends.

Amanita muscaria was also one of the sacred hallucinogenic mushrooms of the Incas, Mayans and Aztecs. Other psychedelic genera included Psilocybe, Paneolus, Conocybe and Stropharia. For the Indians of Mexico, Central and South America, partaking of these mushrooms was a deeply religious experience, enabling them to communicate with their gods. Cortez reported a mushroom (resembling Amanita muscaria) being eaten during the coronation of Montezuma, and in Guatemala stone carvings dating back to 1000 BC depict curious figures with umbrella-like tops resembling the caps and stalks of an Amanita mushroom. Mushrooms are also depicted in ancient Peruvian vessels and in Mexican Codices. One drawing shows an animal-like messenger from god offering the sacred Amanita to a ruler seated on a throne. And a fresco in a Roman Catholic Church in Plaincouralt (Indre), France depicts Adam and Eve on either side of a tree of knowledge that is unequivocally a branched Amanita mushroom.

Some authors have suggested that the original story of Alice's Adventures in Wonderland, where Alice speaks to a green caterpillar who is seated on a red- and white-capped mushroom, is the interpretation of a mushroom experience by the author, Rev. C.L. Dodgson of Christ Church College in Oxford (better known by his pen name of Lewis Carroll). Other students of Amanita and the story of Alice in Wonderland contend that this interpretation is an unsubstantiated rumor. In fact, the selection of a thick-stemmed, red-capped mushroom with white bumps (resembling Amanita muscaria) actually came from the book's illustrator, Sir John Tenniel. Our modern interpretation of the story has certainly been influenced by Tenniel's illustrations. Another hallucinogenic "high" that is commonly depicted in paintings and children's stories is the infamous, "politically incorrect" picture of a witch flying on a broom--the effects of a potion made from the deadly alkaloids of several solanaceous herbs, including jimsonweed (Datura stramonium).

Other hallucinogenic mushrooms, including Psilocybe mexicana and Stropharia cubensis, contain the potent indole alkaloid psilocybin. Indole alkaloids contain the indole carbon-nitrogen ring which is also found in the neurotransmitter serotonin and LSD. These alkaloids may interfere or compete with the action of serotonin in the brain. One of the most amazing stories about naturally-occurring alkaloids in fungi concerns ergot (Claviceps purpurea), a rust fungus that infects grains. The alkaloid of ergot is called ergine (d-lysergic acid amide), better known as natural LSD. [The more potent synthetic LSD is d-lysergic acid diethylamide.] Natural LSD is also found in the seeds of two species of Mexican morning glory vines which are still ingested by native Indians in an important medicinal and religious ritual. During the Middle Ages, thousands of people in Europe were afflicted with ergotism, a malady characterized by gangrenous extremities, convulsions and madness. They ate rye bread infested with ergot fungus containing ergine and several potent vasoconstrictor alkaloids that affected blood vessels. Known as "St. Anthony's Fire," it was a dreaded disease. In case you are wondering, another strong hallucinogenic alkaloid, mescaline, comes from the Mexican peyote cactus (Lophophora williamsii) and the South American San Pedro cactus (Trichocereus pachanoi), and has a chemical structure remarkably similar to the brain neurotransmitter dopamine.

In addition to their uses as mind-altering and spiritual drugs, some mushrooms are commonly taken as healing and preventive medicines. This is especially true in China where herbal medicine has been practiced for countless centuries. The shelflike, woody, reishi mushroom (Ganoderma lucidum) is the Taoist "Elixir of Life." Once reserved for the emperor, it has a long association with longevity and spiritual energy. It is said to improve circulation, reduce cholesterol, lower blood pressure, boost the immune system and has antitumor properties. Long cultivated in Asia, the shitake mushroom (Lentinula edodes) is highly nutritious when cooked and stir-fried in soups and vegetables. Regarded as a revitalizing tonic in China and Japan, it is given to reduce blood pressure and cholesterol, to treat diabetes and cancers, and to enhance sexual energy. Although not native to North America, they can be grown indoors on "shitake logs" available in some specialty stores. The antitumor and antiviral activity of these two Asian mushrooms is thought to be related to the activation of disease-engulfing macrophages and an increased production of helper T-cells.

But of all the marvelous species of fungi on earth, the lichens are perhaps the most fascinating of all. Several hundred million years ago, a most remarkable marriage took place between the vast kingdoms of algae and fungi. Although these diverse kingdoms have survived more than a billion years of evolution, their union into a symbiotic life form called "lichen" enabled them to colonize practically every conceivable habitat on earth. Throughout rain-soaked forests of the world lichens hang in festoons from the tall branches, clothe the trunks and limbs in shrouds of green and gray, and carpet the ground in colorful shades of yellow, orange and red. Lichens flourish under the most extreme conditions, from windswept alpine peaks and frozen Arctic tundra, to sunbaked desert boulders and wave-battered rocky seashores. Lichens have also made themselves at home throughout our urbanized environment, including fence posts and roofing shingles, metal and painted surfaces, concrete and masonry, tombstones and statues, stained glass windows, and on the President's faces at Mount Rushmore National Memorial. But in spite of their amazing tenacity, many lichens are extremely sensitive to atmospheric pollution--a serious human blight that may lead to their extinction in the wild.

Lichen species are conveniently grouped into three characteristic growth forms. Foliose lichens have a leaf-like or lobed thallus, loosely attached to the substrate by root-like rhizines or by a central stalk-like umbilicus. Crustose lichens are low-growing, with the entire thallus firmly attached to the rock or other substrate. Some crustose lichens are called "squamulose" because the thallus is composed of crowded, overlapping scales or squamules. Fruticose lichens have an intricately branched, upright or pendulous thallus. They resemble miniature trees and shrubs, and are commonly used for landscaping model railroad displays.

It wasn't until 1867 that the dual symbiotic nature of lichens was described by the Swiss botanist Simon Schwendener. Schwendener's hypothesis resulted in a bitter controversy among his colleagues who considered the green cells within lichens to be reproductive bodies of the fungus called gonidia. Free-living algae which resembled the green cells were considered to be gonidia which had escaped from the lichen thallus. Writing in Volume 13 of Popular Science Review (1874), the prominent English botanist J.M. Crombie referred to Schwendener's hypothesis as an "unnatural union between a captive Algal damsel and a tyrant Fungal master." Beatrix Potter, an excellent naturalist, writer and scientific illustrator of her time, was a staunch proponent of the alga-lichen hypothesis. In 1896 she wrote a paper on lichens which included meticulous drawings to document her microscopic observations of fungal filaments intertwined with algal cells. Although never officially published, the paper was read at a meeting of the Linnaean Society on April 1, 1897. Beatrix Potter did not attend--as a woman without scientific credentials she was not allowed to appear before such august scientists. Ironically, Beatrix Potter turned her attention to writing the "Tales of Peter Rabbit" and numerous other stories--much to the delight of children everywhere.

The fungal species that form unique symbiotic relationships with algae are called lichenized fungi. They typically belong the fungal classes Ascomycetes or Basidiomycetes. Another term used by lichenologists is "lichenicolous." This refers to specialized fungi that live on the thallus or the ascocarps of lichens. They are different from the lichenized fungi that form the main body of lichens. Lichenicolous fungi belong to three fungal classes, the Ascomycetes, Deuteromycetes and Basiodiomycetes. The photo (left) shows the grayish-brown crustose lichen Aspicilia cuprea growing on a boulder at Cuyamaca State Park. The thallus is areolate, divided into many sections called areoles. A black lichenicolous fungus (Lichenochora verrucicola) is parasitic on the lichen thallus. The dark mass (called a gall) contains several perithecia. The "eye" of an ordinary sewing needle is shown as a size relationship.

Lichens are certainly one of the most successful biological marriages on earth. According to a recent article in Nature (Vol. 378, 1995), the earliest unequivocal fossil lichens date back to the early Devonian (400 million years ago). The algal and fungal partners have survived together for countless millennia and their divorce rate is very low. It is doubtful that most lichenized fungi could have survived to this day without the cooperation of their algal spouse. Likewise, one of the most common algal partners, Trebouxia, is so rare as a free-living alga that it too appears to be dependent on its fungal spouse for survival. At some early stage in evolution, certain species of fungi and Trebouxia may have been faced with near extinction because they were unable to compete with other free-living fungi and algae. Through the competitive advantage of their marriage they have moved from the brink of extinction to their present auspicious status. Now they are facing perhaps the greatest threat to their existence--the pollution of our atmosphere.

Any discussion of the diversity and natural history of fungi would be incomplete without mentioning the remarkable fungus-growing ants of the New World tropics. There are approximately 12 genera and 210 species of fungus-growing ants in the Attini tribe. Two of the genera, Atta and Acromyrmex are more commonly known as leaf-cutter ants. Leaf-cutter ants are an important forest herbivore because colonies containing millions of ants harvest leaves from a variety of plants for their subterranean gardens of basidiomycete mycelia. The leaves that are harvested by workers and laboriously carried to their nests are not eaten by the ants. Instead, the ants use the leaves as a substrate to grow fungus that they farm in special areas of their nests. The fungus provides the ant colony with a nutrient food source. Special enlarged mycelial structures called gongylida are rich in glycogen. The basiomycete for Atta cephalotes and Atta sexdens has been identified as Leucoagaricus gongylophorus = Leucocoprinus gongylophorus.

The ant colony is composed of several castes, including the queen, workers and large soldiers who often stand guard at the entrance of the nest, or even go on scouting missions to protect the colony from predators. Like the queen, the males are winged, and their only role is to inseminate the virgin queen. Workers include larger "media workers" who cut and carry leaf sections back to the nest, and "minima workers" who cut the leaves into minute pieces for the fungus garden. They also cover the leaf fragments with their antibacterial saliva which retards the growth of competing fungi, thus protecting their symbiotic fungus that is vital for their survival. They also feed the entire colony of ants.

Interestingly enough, fruiting bodies (basiocarps) of Leucoagaricus species can be found in urbanized areas of North America, including L. americanus and L. naucinus. The two latter fungi have also been listed in the genus Lepiota.

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