A SHORT 'SHROOM PRIMER

by Wes Stone

THE FUNGUS KINGDOM

Mushrooms are the fruiting bodies of fungi, a kingdom of heterotrophic organisms that reproduce via spores. When you see a mushroom in the forest, you are seeing the equivalent of an apple on a tree. The fungal "tree" or mycelium is underground or buried in the wood or other substrate to which the mushroom is attached. The mycelium consists of bundles of filamentous cells (hyphae) devoted to absorbing and transporting nutrients. Mycelial mats can be huge, sometimes covering acres. When conditions are right, hyphal bundles will differentiate to form mushrooms. The mushrooms contain specialized reproductive tissues critical for spore production. Fungal sex is unusual and complicated, and a subject best explored on one's own.

MUSHROOMS: THE MEAT OF THE MATTER

In the Pacific Northwest, we are blessed by the presence of the temperate coniferous rainforest. Many of our fungi show an affinity for the forests, and depend on trees to live. Fungal relationships with trees may be parasitic, saprophytic, or mutualistic. In parasitic relationships, the growing fungus harms the host tree while gaining nutrients from it. Many of the conks (Ganoderma and Fomitopsis species) are parasitic. More numerous are the saprophytic fungi, which live and feed on dead trees or tree debris. Good edibles from this group are the oyster mushrooms (Pleurotus and Pleurocybella species) and Boletus mirabilis. Many of the fungi on the forest floor have a mutualistic relationship with trees. In this situation, also known as a mycorrhizal relationship, the fungal mycelium and tree root intergrow. The mycelium absorbs inorganic nutrients easily, and these can be passed to the tree through the mycorrhizal bond. The tree provides moisture and organic compounds to the mycelium, and keeps the mycelium anchored in the soil.

Mycorrhizal relationships can be complex, as some fungal species will form them with only a single tree species and some individual trees may have many associated fungi. The inability to recreate mycorrhizal conditions is the main reason that some commercially valuable mushrooms (morels, chanterelles, and matsutakes) are difficult to cultivate in a farm environment. Also, tree plantations that lack mycorrhizal fungi grow more slowly and are more susceptible to disease than those where the fungi are present.

FINDING MUSHROOMS

As stated above, mushrooms form only when fruiting conditions are favorable. For every mycelial patch of every species in every habitat in every region, a different set of conditions will spur fruiting. In Western Oregon, the majority of prominent mushroom species will fruit from the first fall rains until the first extended cold spell. There are plenty of exceptions, such as fungi that fruit in the spring after snowmelt (Morchella and Gyromitra species) and fungi that fruit in both spring and fall (Agaricus augustus and Boletus edulis, to name two of the best edibles). Certain mushrooms will be found with certain trees, and some prefer urban habitats. Beyond this, few generalizations can be made. More information will be given in the section on specific mushrooms. The trick is to find a patch and check it regularly. In hunting mushrooms for the table, you face stiff competition from maggots and slugs as well as severe weather. The odds are not on your side...

IDENTIFYING MUSHROOMS

There are two time-tested ways to identify mushrooms if you are interested in eating them and surviving. The first is to go out into the field with experienced collectors and learn each mushroom on an individual basis until you are thoroughly familiar with its appearance and habits. The second is to get some books on mushroom identification and learn to identify mushrooms based on diagnostic features. Each method has its advantages and disadvantages, but the best course by far is to combine both. You will end up finding and eating more mushrooms by tapping books and people than by relying on either resource by itself.

Avid mushroom hunters learn to spot-identify mushrooms that a beginner might spend hours trying to key out. Once one has seen a species in a variety of habitats and conditions, identification becomes second-nature. Chanterelles, which can only be keyed out by noting the blunt ridges on the underside of the cap, are easily recognized from above by experienced pickers. Experience is the key, and leads to self-confidence and a greater appreciation for fungi as foods and organisms rather than just something that might be toxic.

The preferred books on mushroom identification contain dichotomous keys. Such a key begins with a pair of statements (couplet) that could describe a mushroom. For example:

1. Very base of stalk giving off an unpleasant odor when crushed;

base sometimes also staining yellow when cut or crushed ...... 2



1. Not as above; odor not unpleasant; base of stalk typically not

staining yellow, or if staining yellow then odor sweet ....... 7
In this key couplet (adapted from Arora 1986), one should crush the base of the stalk and smell it, watching for color changes. If the odor is unpleasant, one would proceed to couplet 2 in the key. If the odor is not unpleasant, one would proceed to couplet 7. The information on staining might be helpful if one cannot discern an odor. The next couplet may imply that another test should be performed, such as a spore print or chemical stain. Or, it may ask about the color or size of the fruiting body. Eventually, by following the key and making the right choice each time, a positive identification is made.

The key method has obvious flaws. For one, a mistake at the beginning of the key may lead one far astray, so that the final identified mushroom is not even closely related to the actual specimen. For another, keys rely on characteristics such as color and odor, which may vary with environmental influence and may be perceived differently by different individuals. The results of a mistake can be disastrous. As the old saying goes: "When in doubt, throw it out!" While keys will never be airtight, they can be improved when accompanied by full descriptions of the mushrooms. If certain tests cannot be performed, or a couplet is ambiguous, consulting a good description of the mushroom should relieve doubt in most cases. Doubt is further decreased if you consult with an experienced collector.

IDENTIFYING FEATURES

Figure 1 shows just a few of the anatomical features that mushrooms may possess. None of these features is universal in mushrooms, but typical gilled mushrooms possess a cap and usually a stalk. The fertile surface where spores are produced is often on the underside of the cap. It may consist of bladelike, radiating gills, as in the grocery store mushrooms. The gills vary between species in their point of attachment to the stipe and/or cap. Other fertile surface arrangements include pores (as in the boletes) and teeth (as in the edible hedgehog mushroom). It is preferable to have a few specimens on hand to illustrate these, although pictures may suffice. The stipe may be off-center or absent, especially in mushrooms growing on wood. The cap may be smooth, or may have attached particles as shown here. The annulus, when present, is the remnant of a partial veil that covers the gills of young mushrooms and breaks at maturity to form a ring on the stalk. In some groups (notably the Amanitas), an additional, universal veil covers the entire mushroom and breaks to form a cuplike volva at the base of the stipe. Like the cap, the stipe may be smooth or roughened. Cap and stipe shape may sometimes be used as identifying characteristics; this mushroom has a convex cap and a stipe with a basal bulb.

Color and Staining Reactions. Many mushrooms have a distinctive color, and color features are often used in keys. Color is rarely (if ever) constant within a species, and varies with environmental conditions. Golden chanterelles (Cantharellus cibarius) that fruit in dry weather tend to be flesh-colored. Moisture extremes and the age of the mushroom play a big role in determining the color, so colors are usually expressed as a range (e.g., dark brown, sometimes fading to tan or even off-white). Color perception is subjective; not everyone will agree that yellow is yellow rather than creamy or orange. Obviously, color can never be used alone as an identifying characteristic, but it is always useful as one of many characteristics.

Many mushrooms undergo color changes when cut or bruised. These changes may be observed over the whole mushroom, or may be restricted to one location. The mildly poisonous Agaricus praeclaresquamosus, for example, stains bright yellow in the very base of the stipe. The pores of many boletes (fleshy pore mushrooms) stain blue. The intensity and speed of color changes vary, again, with environmental conditions. Some staining reactions are latent, in that they occur only when a drop of chemical solution is applied to the mushroom. Generally, the more common and distinctive mushrooms can be identified without resorting to laboratory techniques.

Odor and Taste. We rely on senses other than our eyesight to identify mushrooms. Odor is important in identifying some key species. Once you have become familiar with the smell of the white matsutake (Tricholoma magnivelare), you will be able to identify it with your eyes closed! Unfortunately, smells are harder to describe than are colors, and a lot of people seem to be "smell-blind". Occasionally, a key will ask you to taste a mushroom. Take a small piece of the cap, put it in your mouth, chew on it, and spit it out. Most mushrooms have a mild flavor when raw; they don't really taste like much. A few mushrooms are sweet, and a significant number are bitter or peppery.

Spore Prints. Spore color is used to place many mushrooms into taxonomic groups, and is often used in keys. To obtain a spore print, cut the cap off a mushroom and place it upright (fertile surface down) on a sheet of white paper or an index card. Let the mushroom sit overnight, then examine the paper. If the mushroom was discharging spores, a radiating deposit of spore dust should be visible on the paper. Some mushrooms have white spores; in this case, the deposit can best be seen if the paper is viewed from the side. Other colors of paper may allow for easier detection of spores, but for critical color discrimination (between white and cream or yellowish, for example) white paper is standard. Only mature, relatively fresh mushrooms will give good results.

Textures. The different parts of a mushroom can have different textures. The stipes of Russula and Lactarius species are crisp and break cleanly, whereas Armillaria mellea has a fibrous stipe. A mushroom's cap may be viscid (sticky/slimy) or dry. The overall texture of a mushroom may be described as fleshy, woody, gelatinous, or rubbery, among other adjectives.

Gill Attachments. Gills (or pores or teeth) may be attached at different points. Free gills are attached only to the cap, as in Agaricus. Adnate gills attach to the stipe, and decurrent gills run down the stipe. The chanterelles have a decurrent fertile surface.

As evidenced by the above list (which doesn't even scratch the surface), many attributes are used to identify mushrooms, from gross anatomical features to microscopic distinctions in spore size. No single characteristic can be used, by itself, to determine that a mushroom is edible (although several, such as a noxious odor or excruciatingly peppery flavor, work fine for determining that a mushroom is inedible). Anyone venturing into the world of mushroom identification is advised to have access to a couple of good field guides. For amateur mycologists in the Western United States, the best print resource is Mushrooms Demystified by David Arora (Ten Speed Press, Berkeley: 1986). Most of the mushrooms likely to be encountered are keyed out, most of these are given full descriptions, and identifying features are given for each taxonomic grouping. The Audubon Society Field Guide to North American Mushrooms (Lincoff, Gary, Ed., Knopf, New York: 1981) does not contain dichotomous keys, but the numerous first-rate color photos make it a good companion to Arora's book.

MAJOR GROUPS OF FUNGI

When we think of mushrooms, we generally picture them as having gills. As I alluded to above, this is not always the case. Gilled mushrooms belong to the order Agaricales. Gills are the distinguishing feature of this order, but fleshy mushrooms with pores (the boletes) are also included. The Agaricales are part of a larger division of fungi, the Hymenomycetes. Other orders in the Hymenomycetes include the Aphyllophorales (the polypores, chanterelles (sometimes placed in their own order), coral fungi, and teeth fungi), as well as the Tremellales (the jelly fungi). The Hymenomycetes, in turn, are part of a larger super-division, the Basidiomycetes. The key feature of the Basidiomycetes is actually microscopic and involves the structure of cells on which spores are produced. Besides the Hymenomycetes, the Basidiomycetes include the puffballs and earthballs in the subdivision Gasteromycetes.

Some common fungi, such as the morels, cup fungi, Hypomyces molds, and truffles, belong not to the Basidiomycetes but to the Ascomycetes, which produce spores inside rather than on the surface of specialized cells. There are several other major groups of fungi, but they mostly contain microscopic organisms that do not produce mushrooms.

EATING MUSHROOMS

Obviously, one can enjoy mushrooms without eating them. For many, however, eating mushrooms is a cultural tradition or at least an end to collecting. Mushrooms can add texture, color, and flavor to food. There are deadly mushrooms out there, but there are also deadly plants (such as water hemlock, which has been mistaken for wild parsley). The reason we aren't afraid to eat plants is because they have been domesticated. Fungi, with the exception of Agaricus bisporus and a few other cultivated species, are untamed. The burden of identification is on the collector. Because most fungi have not been eaten throughout the world for most of human history, there is always a possibility that some people's bodies will not be able to handle some of the unique compounds present in fungi. While most people may pronounce a given fungus edible and delicious, an unfortunate few may be unable to metabolize some chemical in that fungus. Such "allergies" are generally not serious, and usually result in a short period of nausea and vomiting. A few species seem to be implicated in comparatively many allergy cases (including such popular mushrooms as morels, Agaricus species, and Boletus edulis). This is no reason to be overly concerned; we still drink milk even though some people are lactose intolerant.

Getting the identification right is the most important thing to do before eating a mushroom. If possible, get an experienced collector's confirmation or view a type specimen before eating a new mushroom species. Try only a few bites the first time you eat a species, then wait at least a day before consuming any more. Always cook mushrooms the first time you try them; most wild mushrooms are more digestible when cooked. There are many other cautions and hints about eating mushrooms; these can be found by consulting the reference materials at the end of this primer.

MUSHROOMS, THE ENVIRONMENT, AND YOU

Mushroom collecting for food and as a hobby is increasing in popularity. While the American view of the world has traditionally lumped fungi in with plants, or disregarded this group of organisms altogether, fungi have recently achieved a greater prominence in our culture. Resurgent interest in mushrooms as medicinal sources has had some effect, but the most attention seems to be centered on mushrooms as a profit-making, commercial resource. Mushrooms have always been picked for the market, but the market in the past was relatively small and mostly limited to ethnic constituencies such as Japanese-Americans and Italian-Americans. Within the past five years, an export market for mushrooms has developed and made mushroom-picking a big business. One mushroom in particular has been responsible. Between 1989 and 1990, the reported commercial harvest of matsutake mushrooms (Tricholoma magnivelare) increased by over 4000% in the state of Washington (Molina et al, 1993).

The increasing use of federal lands for commercial activities has led to increased regulation of both commercial and recreational mushroom picking. In Oregon, a variety of areas including most Wilderness Areas and all State Parks are now closed to any mushroom harvesting. Recreational regulations differ between National Forests within Oregon: Some allow limited "incidental" harvest of mushrooms without a permit, and others require a free use permit for any picking. Because of the value of matsutake mushrooms (which collectors sold for an average price of $13.99 per pound in 1989, according to Molina et al, 1993) special regulations are under effect for these mushrooms. The Willamette, Umpqua, Winema, and Deschutes National Forests require a commercial permit with a minimum cost of $50 to harvest any matsutakes, although the regulations have recently changed to allow limited incidental harvest with a special permit in designated areas. The Mt. Hood National Forest allows free-use collection of matsutakes, with the stipulation that collected mushrooms will be cut in half to prevent their commercial resale. The Siuslaw National Forest allows for the harvest of up to six matsutakes per day as part of the incidental harvest limit, as long as the mushrooms are scored to prevent resale. Permit conditions are continually changing as new regulations are adopted.

With the growth of the commercial industry, there has been an increase in concern about protecting the mushroom resource. Both overharvesting of mushrooms and incompatibility with forest practices such as timber harvesting could potentially impact the availability of this resource. Forest ecologists and soil biologists have long known the importance of mycorrhizal fungi to the forest ecosystem. This knowledge is just now becoming widespread, and will surely be used in future debates over forest practices.

Despite the regulations, amateur mycology and mushroom collecting are still fun activities. The collection presented here shows that interesting mushrooms are within walking distance. Mycological organizations abound, and many community colleges and recreation departments offer classes in mushroom identification. With a little effort, anyone can begin discovering the overlooked world of fungi.

REFERENCE MATERIALS

IDENTIFICATION AND FIELD GUIDES

Arora, David. Mushrooms Demystified. Ten Speed Press, Berkeley: 1986.

This is the most comprehensive field guide to species of the Western United States. I recommend that you include it in your library. Arora has also authored a more compact field guide, but the price difference isn't that much. If you own only one book about mushrooms, this should be it.
Fischer, David and Alan Bessette. Edible Wild Mushrooms of North America: A Field to Kitchen Guide. University of Texas Press, Austin: 1992.
Designed for the mushroom hunter whose main question is: "Can I eat it?", this guide contains descriptions of edible mushrooms and their poisonous look-alikes, along with preserving and cooking ideas.
Lincoff, Gary H. and Carol Nehring. The Audubon Society Field Guide to North American Mushrooms. Knopf, New York: 1981.
If you're serious about mushrooming, you should own more than one book. This is a good picture reference guide, with a visual rather than dichotomous key. It also contains species from throughout North America.
TECHNICAL REPORTS

Molina, Randy, with Thomas O'Dell, Daniel Luoma, Michael Amaranthus, Michael Castellano, and Kenelm Russell. Biology, Ecology, and Social Aspects of Wild Edible Mushrooms in the Forests of the Pacific Northwest: A Preface to Managing Commercial Harvest. U.S. Department of Agriculture, Forest Service, Portland, Oregon: 1993. PNW-GTR-309.

This is an eye-opening little publication that shows just how far-reaching commercial and recreational harvesting of wild mushrooms could become. Ten mushroom species with commercial potential are profiled, and the history and future of mushrooms in forest management are outlined.
Pilz, David and Randy Molina, ed. Managing Forest Ecosystems to Conserve Fungus Diversity and Sustain Wild Mushroom Harvests. U.S. Department of Agriculture, Forest Service, Portland, Oregon: 1996. PNW-GTR-371.
A progress report on research into the effects of timber and mushroom harvesting on the sustainability of the mushroom resource.
ELECTRONIC RESOURCES ON THE WORLD WIDE WEB

Dhabolt, John. mycoElectronica

Mushroom information ranging from toxicology to philately (stamp collecting).
Fischer, David. Dave Fischer's Mushroom Page

Harrison, Wayne. Mycelium NOTE: NO LONGER AVAILABLE

Mycelium is a Web page devoted to amateur mycology. Mycological society journals and foray reports are archived, and there are mushroom recipes, book reviews and links to other mycological URLs. A list of mycophiles (people who like mushrooms) on the Internet is maintained here.
Stone, Wesley H. The Forager Home Page
This is a shameless plug for my own page. Archived here is a list of all the mushroom species I have identified on the Lewis and Clark College Campus, information on other wild foods, and recent personal foray reports.
Wood, Michael. Myko Web
Loads of mushroom stuff from a past president of the Mycological Society of San Francisco.
Wood, Michael and Fred Stevens. Common Fungi of the Bay Area
Good photos and descriptions of a bunch of suburban mushrooms; many of these same species can be found around Lewis and Clark!
PERMIT SYNOPSES

U.S. Department of Agriculture, Forest Service. Mushroom Permit Synopsis for Deschutes, Winema, Willamette, and Umpqua National Forests, July 1 thru December 31, 1996.

U.S. Department of Agriculture, Forest Service. Free Use Mushrooms Forest Products Removal Permit. (Mt. Hood National Forest, Zigzag Ranger District). Form Adopted January 1996.

U.S. Department of Agriculture, Forest Service. Permit Conditions: 1995 Mushroom Picking on the Siuslaw National Forest. Form Adopted June 1995.

For more information, please contact the agency in charge of the land from which you wish to collect. Regulations change frequently.


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