A mushroom (or toadstool) is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source.
Mushrooms are a low-calorie food eaten cooked, raw or as a garnish to a meal. In a 100 g (3.5 ounce) serving, mushrooms are an excellent source (higher than 20% of the daily value, DV) of B vitamins, such as riboflavin, niacin and pantothenic acid, an excellent source of the essential minerals, selenium (37% DV) and copper (25% DV), and a good source (10-19% DV) of phosphorus and potassium. Fat, carbohydrate and calorie content are low, with absence of vitamin C and sodium.
There are many distinctive shapes or forms of mushrooms. Gilled mushrooms (agarics) differ from boletes and polypores by the shape of their fertile spore-producing layer, the hymenium. Morels, with their pitted hymenium are quite distinctive from coral fungi that have a smooth hymenium. For stipitate fungi (those having stems), the attachment of the cap and stem may be ‘central’, ‘lateral’ or ‘reduced’. Some mushrooms, such as the giant puffball (Calvatia gigantea) have no stipe. Fungi of the truffles form produce their spores on the inside of there fruiting body, and often fruit below the soil or at the soil surface.
When looking a cap there are a number of thing to look for. Firstly, there are the obvious characteristics of size, and colour. The shape of the cap is also useful, but it must be remembered that this is very likely to change as the fruit body matures. If you look at the surface of the cap does it have scales or obvious fibres? Is it dry, greasy or slimy?
Spore color and shape
It is possible to get spore prints from a wide range of fungi including agarics, boletes, morels, coral fungi, and resupinate fungi. Often times, fungi have ‘spore-printed’ themselves, and you will see spores dusting the caps, along the stem or at the base of the mushroom. To obtain a spore print place a section of spore producing tissue on a piece of paper, cover to keep the humidity high, and place in a cool dark environment. Note the spore color after a few hours. Spores can range in color from white, buff, pink, tan, chocolate brown, rusty brown to black. With a compound microscope spore, diagnostic features including spore shape, size and ornamentation can be observed.
The presence or absence of veils
A veil is a thin tissue the covers the spore-producing hymenium before the mushroom reaches maturity. Veils are common in some groups of mushrooms and boletes. They are most evident in young fruiting bodies. Many produce fragile or cobwebby veils that quickly disappear or weather away. Superficial wisps of tissue around the apex of the stem or the margin of the cap may be all the remains of a partial veil. Other times veils form a collar around the mushroom stem and are strikingly evident. In other cases, such as in deadly toxic species of Amanita, fruiting bodies are form in a sac-like structure, known as a volva, which is evident at the mushrooms base.
Types of mushroom veils:
Hymenium (the fertile tissue)
Underneath the cap you will normally find gills. The Boletes, however have pores and some other species even have spines. When looking at the gills (or pores/tubes) note their colour, thickness and how crowded or widely spaced there are. Do they break easily? When you cut the cap in half how deep are the gills? A small mirror can place under a mushroom in the field to observe this character without disturbing the fungus.
The attachment of gills to the mushroom stem can be:
Free – The gills don’t join the stem at all but curve-up to join directly back onto the cap
Adnate – The gills again curve up but join near the top of the stem
Adnex – The gills neither curve up nor down but join directly onto the stem
Sinuate – This is a combination of the previous two. The gills curved upwards but then curve back down as they join the stem
Decurrent – The gills curve down the stem
The gill margin (distant edge) may be smooth or saw-toothed, and the color may be distinct. The gill spacing and thickness also varies between groups of fungi. Some have forking and cross-venation in their gills. In pored fungi, the shape and size of the pores varies.
Spacing of gills:
It’s very important to ensure that you have the complete stem when trying to identify a specimen as some characteristic features appear at the very base of the stem.
The two major features which may be present on the stem are the ring and the volva. The ring is a thin collar around the upper portion of the stem. The volva is a bag-like structure around the base of the stem.
Again, general observation should include size, colour, and shape. Is the stem cylindrical or does it taper from the top or bottom. Does it have a distinctly bulbous base? Does it have a circular cross-section or is it flattened? Is it smooth, rough or scaly
The following are some types of stem morphologies used in mushroom identification:
Texture and color change
Mushroom and truffle tissues vary in texture and can change color when handled. For instance, tissues of some boletes bruise blue when handled, due to oxidation reactions. Such reactions can be a diagnostic feature. When the cap or stem of mushrooms is damaged, it may stain red, yellow, green, blue or purple, or may not stain at all. Tissues may ‘peel’, ‘break’, may feel ‘slimy’ or ‘spongy’ or may be ‘woody’ or ‘fibrous’. The peridium, or outer surface of truffles, vary in texture and can range in color, texture (from smooth to warty), thickness and cellular arrangement.
The odor of fungi can be an important character for identifying some types of mushrooms and truffles. While subjective and variable between individuals, some fungi have distinctive odors that may range from ‘fruity’, ‘nutty’, ‘mushroomy’ to ‘phenolic’ or ‘putrid’.
Season, geography, weather
Mushroom species are adapted to certain places and conditions. Making note of the location (GPS coordinates are standard), time of year, and recent weather conditions and (day and night) temperatures can be helpful in identifying fungi, as are digital photographs of fresh specimen, paying special attention to the characters outlined above. Reputable taxonomic keys and field guides of the region of collection should be referenced for identifying fungi.
If you cut the fruit body in half the flesh may offer other clues as to the fungi’s identity. The colour of the flesh is sometimes different from the colour of the skin. A surprising feature of some fungi is that the flesh changes colour when exposed to air. So the flesh may appear yellow when first cut and then turn blue. These colour changes can be almost instantaneous or happen gradually over a couple of hours.
Another useful features of the flesh to observe are its texture (woody, fibrous, soft, crumbly). The group of fungi called the Milkcaps exude fluid when cut (even from the smallest cut). The presence of this fluid (called latex) is enough to show that you have a Milkcap. The colour of the latex is useful in helping to decide which of the Milkcaps you have.
Adnate – The gills join the stem to the full depth of the gill. Neither curving up to the cap or running down the stem.
Adnexed – The gills join the stem to a part depth of the gill. The gills are seen to curve up towards the cap, but do join the stem.
Cortina – A cobweb-like network fine threads joining the edge of the cap and the stem. This provides protection for the young gills in some species (e.g. the Web Caps).
Cortinal zone – The remnant of the cortina found on the stem after the cap has expanded.
Decurrent – The gills are seen to curve down along the stem.
Eccentric – Off-centre – usually with reference to the position of the stem relative to the centre of the cap.
Fibrillose – Covered in small fibres
Free – The gills are seen to curve up and join the cap. They do not join onto the stem at all.
Gleba – The spore bearing tissue in the centre of stomach fungi (puff balls, earth balls and earth stars)
Latex – Fluid exuded by Milkcap fungi when damaged. It is usually cloudy and often white, but in some species may be yellow orange, red or even clear.
Mycelium – The mass of thread-like or felt-like fibres that make up the hidden ‘body’ of a fungus.
Pellicle – An easily detached skin or cuticle on the cap of a fungus
Pore – The mouth of a tube on a Bolete or ploypore fungus
Ring – The remains of partial view left attached to the stem.
Ring zone – Mark left on the stem which indicated where the partial veil was attached.
Scurfy – Rough or velvety, covered in small scales.
Sinuate – The gills join the stem to a part depth of the gill (as with adnexed) but then curved down (as with decurrent) just before joining the stem. Appears as a small notch in the gills just before the stem.
Spore – These are the microscopic ‘seeds’ of the fungus
Spore print – A deposit of spores from a cap placed for several hours on a flat surface (often paper). The colour of the deposit is used as an identifying feature of fungi.
Stipe – Another word for the stem of a fungus which supports the cap
Striated – Covered in fine lines. Often used to describe thin parallel lines around the edge of a cap.
Tubes – The spore bearing structures of Boletes and Polypores. They form a layer under the cap.
Umbo – A central hump or boss in the middle of the cap.
Umbonate – With an umbo.
Veil – A sheet of tissue used to protective a fungus during its development. A universal veil encloses the entire fruit body. A partial veil joins the cap to the stem protecting the gills.
Volva – The remains of a universal veil forming a cup-like bag around the base of the stem.
For the past years I’ve been studying and foraging wild mushrooms.
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Commonly foraged species
The Macrolepiota genus, usually the Macrolepiota procera, and, to a lesser extent, the M. rhacodes are highly regarded, especially in Europe, being very palatable and very large, with specimens of M. procera as high as one metre being reported.
- Agaricus bisporus also known as the table or button mushroom. Sales of this mushroom in 1996 reached $209 million in Canada.Another well known mushroom known as the portobello is a large brown strain of this fungus.
- Coprinus comatus (shaggy ink cap) decomposes into ink, and hence are prepared soon after picking and only young specimens are collected. While being a general mushroom hunting guideline, the avoidance of specimens growing in areas with high pollution is especially important with this family, as it is a very effective pollutant absorber.
- Macrolepiota procera (parasol mushroom)
While the family of Amanitas are approached with extreme caution, as it contains the lethal Amanita phalloides and Amanita virosa, those confident in their skills often pick theAmanita rubescens, which is highly prized in Europe and to a much lesser extent in Russia, accounted by some not to superior taste, but to its relation to the Amanita caesarea, which is not found in Russia, but was considered a delicacy worthy of the emperor in Ancient Rome.
This order is often viewed as the order of “noble” mushrooms, containing few poisonous species, identifiable with relative ease, and having superior palatability. The most notable species is the Boletus edulis, the “mushroom king”, an almost legendary, relatively rare mushroom, edible in almost any (even raw) form, and commonly considered the best-tasting mushroom. (It is common to confuse the Russian name, literally “white mushroom”, with champignons, often known in English as “white mushrooms”.)
- Boletus edulis (Hřib Smrkový, Dubák, Borowik szlachetny, Porcino, King Bolete, Cep, Steinpilz)
The Leccinum genus includes two well-known mushroom species named after the trees they can usually be found next to. The Leccinum aurantiacum (as well as the Leccinum versipelle), found under aspen trees, and the Leccinum scabrum (as well as the L. holopus), found under birch trees. The secondary mentioned species, are significantly different in cap colour only. Both types are very sought after, being highly palatable, while more common than the B. edulis.
The Suillus genus, characterised by its slimy cap, is another prized mushroom, the Suillus luteus and Suillus granulatus being its most common varieties, and while abundant in some parts of Eurasia, is a rare occurrence in others. It is easy to identify and very palatable.
- Suillus (klouzek, slippery Jack, butter mushroom)
The Xerocomus genus is generally considered a less desirable (though mostly edible) mushroom group, due to common abundant mould growth on their caps, which can make them poisonous. The Xerocomus badius, however is an exception, being moderately sought after, especially in Europe. Some scientific classifications now consider species in theXerocomus genus as members of Boletus.
The Cantharellus cibarius, a common and popular mushroom, especially in Europe, is a choice edible and unique mushroom. It is very rarely infested by worms or larvae, has a unique appearance, and when rotting, the decomposed parts are easily distinguishable and separable from those that are edible.
- Cantharellus cibarius (chanterelle, yellow chanterelle, pfifferling)
The Gyromitra esculenta is considered poisonous, but can be consumed if dried and stored for over a year, according to Slavic literature, and can be used to supplement or replace morel (see Morchellaceae below) mushrooms, while Western literature claims that even the fumes of the mushroom are dangerous. It is similar to morels both in appearance and palatability.
- Gyromitra esculenta (false morel, beefsteak morel, lorchel)
The morel, Morchella esculenta is highly prized in Western Europe, India and North America. It is significantly less prized in Slavic countries where, like the Gyromitra esculenta, is considered marginally edible with mediocre palatability. Boiling the mushroom and discarding the water is often recommended.
- Morchella esculenta (morel, yellow morel)
Members of the genus Lactarius, as the name suggests, lactate a milky liquid when wounded and are often scoffed upon by Western literature. The Lactarius deliciosus is however regarded as one of the most palatable mushrooms in Slavic culture, comparable to theBoletus edulis. Also considered as similarly palatable are the species Lactarius necator and particularly Lactarius resimus. Thermal treatment may however be necessary in some cases. Slightly less appealing due to its bitter taste is the Lactarius pubescens.
- Lactarius deliciosus (saffron milk-cap)
- Lactarius resimus (pepper cap)
- Lactarius necator (black pepper cap)
- Lactarius pubescens (wooly milk-cap)
The Russula family includes over 750 species and is one of the most common and abundant mushrooms in Eurasia. Their cap colours include red, brown, yellow, blue and green and can be easily spotted. The Russula vesca species, one of the many red-capped varieties, is one of the most common, is reasonably palatable and can be eaten raw. The edible Russulas have a mild taste, compared to many inedible or poisonous species that have a strong hot or bitter taste. TheRussula emetica (the sickener) is known to cause gastrointestinal upset and has a very hot taste when a small bit is placed on the tongue. Due to their abundance they are however often regarded as an inferior mushroom for hunting.
- Russula vesca (Russula)
- Armillaria (honey mushroom, shoestring rot). The genus Armillaria, with the popular species A. gallica and A. mellea, being so similar that they are rarely differentiated, are palatable, highly abundant mushrooms. Generally found on decaying tree stumps, they grow in very large quantities and are easy to spot and identify, arguably reducing the fun and challenge in mushroom hunting.
- Pleurotus ostreatus (oyster mushroom). It is the most commonly picked tree-dwelling mushroom and is often also artificially cultivated for sale in grocery stores. This sturdy mushroom can be quite palatable when young. Growing these mushrooms at home can be a profitable enterprise and some Russians engage in the activity.
- Tricholoma matsutake – = syn. T. nauseosum, the rare red pine mushroom that has a very fine aroma. Its fragrance is both sweet and spicy. They grow under trees and are usually concealed under fallen leaves and the duff layer. It forms a symbiotic relationship with the roots of a limited number of tree species. In Japan it is most commonly associated with Japanese red pine. However, in the Pacific Northwest it is found in coniferous forests of Douglas fir, noble fir, sugar pine, and Ponderosa pine. Farther south, it is also associated with hardwoods, namely tanoak and madrone forests. The Pacific Northwest and other similar temperate regions along the Pacific Rim also hold great habitat producing these and other quality wild mushrooms. In 1999, N. Bergius and E. Danell reported that Swedish (Tricholoma nauseosum) and Japanese matsutake (T. matsutake) are the same species. The report caused the increased import from Northern Europe to Japan because of the comparable flavor and taste. Matsutake are difficult to find and are therefore very expensive. Moreover, domestic productions of Matsutake in Japan have been sharply reduced over the last fifty years due to a pine nematodeBursaphelenchus xylophilus, and it has influenced the price a great deal. The annual harvest of matsutake in Japan has since further decreased. The price for matsutake in the Japanese market is highly dependent on quality, availability and origin. The Japanese matsutake at the beginning of the season, which is the highest grade, can go up to $2000 per kilogram, while the average value for imported matsutake from China, Europe, and the United States is only about $90 per kilogram.
- The Tricholoma magnivelare is a prized mushroom in North America. British Columbia exports large quantities of this mushroom overseas to Asia where it is in high demand.