By Rick Snider
After a rainy spell in late summer or fall, look closely along trail edges and in woods or fields and you are sure to see some of the roughly 2000 species of mushrooms that could be growing there. Store mushrooms tend to be brownish with a stalk and a cap but wild ones can look very different. Some are jelly-like blobs with bright eye-catching red and yellow colours, while others look like tiny bird’s nests or hang like white icicles. Some are tiny and delicate, almost microscopic in size, and some like the Puffball can be a few feet across. While most have a mild earthy aroma, the Stinkhorn fills the air with a putrid smell.
There are poisonous ones and edible ones and some, like Truffles, are a gourmet delight. With all this variety, mushrooms are a fascinating group of organisms.
What we see above ground, commonly referred to as the mushroom, is the reproductive part of a fungus. It is a small and short-lived, somewhat like fruit on a tree. The bulk of the organism is comprised of tiny cylindrical threads, present year round, under the surface of the ground. As the fungal threads grow longer they sometimes interconnect, forming large dense masses. Only when conditions such as moisture and temperature are just right, usually after rains, do they send up a fruiting body above the ground. Green plants have seeds, but mushrooms reproduce by tiny spores on the underside of the mushroom cap. These are eventually released or ejected and disperse in the wind to form new fungi if they land in just the right spot.
Ninety per cent of all organisms in the soil are fungi, the rest being earthworms, insects, bacteria, and other tiny living things.
Many fungi are decomposers. Their fungal threads penetrate dead wood and plant material, secrete digestive enzymes that contribute to the plant decay, and then absorb nutrients that are released during the process. This way they obtain the energy food called glucose, which is stored in the plant tissues and was made by the plant when it was living.
Not all fungi are decomposers.
Some, equally important ones live in close association with tree roots and assist the tree to obtain the nutrients it needs. In fact some trees have hundreds of thousands of kilometres of these special fungal threads, growing so densely they form a network or layer around each root hair and provide water and nutrients to the tree. In exchange, the tree gives to the fungus the glucose produced in its leaves, so both the tree and fungus benefit from the partnership. These fungi that live in close association with tree roots are called micorhizzal (mike–o-rise-al) fungi and it is now thought that most, if not all, trees need this fungal association for the best growth.
Several toxins have been found in wild mushrooms.
Some containing deadly toxins have appropriate names like the Destroying Angel, Death Cap, and Deadly Galerina. It is very important to positively identify every wild mushroom you may be thinking of eating because some poisonous varieties resemble edible ones. The toxic chemicals found in mushrooms can cause mild to severe intestinal discomfort or worse. The really dangerous toxins that lead to death affect the kidneys and liver. The symptoms of some lethal poisons do not occur until many hours or even days after eating, but then a painful death follows. As a rule of thumb if you have intestinal discomfort shortly after eating a mushroom, you may be lucky; the timing suggests a non-lethal toxin, but you should seek medical attention immediately in any case, and it is wise to keep an uncooked sample for later analysis in case of a problem.
To compound the problem, some people do not react to mushrooms that make others very ill, so the “I eat it all the time with no problem” recommendation doesn’t mean you are home free. In the past a mushroom sold in European markets and enjoyed by most people with no ill effects, was taken off the market because it was found to be poisonous for a small number of consumers.
But not to scare everyone off with information on mushroom poisoning, there are, of course, lots of edible ones and those who enjoy eating wild mushrooms know how delicious they can be. Some choice edibles have names like: Horn of Plenty, Chicken of the Woods, and Oyster Mushroom. Others such as Chanterelle and Truffles are gourmet delights.
Some edible mushrooms, Giant Puffball for instance, are very distinctive and easy to recognize with confidence, others have to be identified with more care. Even experienced mushroom collectors will pass up possible edibles if they are not 100 per cent positive of the identification.
Beginners should not take any chances unless the mushroom is first identified by an authority.
There are many field guides to mushrooms but most cover Europe or Western North America. The best field guide for Ontario is “Mushrooms of Ontario and Eastern Canada”, authored by George Barron, and published by Lone Pine Publishing. This excellent book is easy to read and contains a treasure of information on mushrooms, not just their identification but other interesting aspects of fungi in general. It identifies edible and poisonous ones, and includes photos of 609 mushroom species most likely encountered in the area. George Barron is an honoured mycologist retired from the University of Guelph.
Even if you know the location of an edible mushroom, commonly referred to as an “edible”, you have to check it frequently because it is not easy to predict when they will appear. Most edibles are seasonal to a degree, with late summer and fall being the best, but even within the right season you have to find your mushrooms as soon as possible after they appear, while they are still fresh. They grow quickly and can form overnight after a rain. Mushroomeating slugs often find them before you do, and after a day or two they wither and start to decay. Collectors put mushrooms in old-fashioned wooden baskets or brown paper bags because they wilt rapidly in plastic bags.
If a fungus grows outwardly in a circular fashion and mushrooms fruit on the outer edge of this circle, they form a “Fairy Ring”. About 60 species of fungi do this, forming rings in lawns and woodlands. The size of the ring can be from a few inches to many feet or even larger. In Medieval times in Europe, Fairy Rings were considered magical and anyone who stepped into one could suffer dire consequences such as uncontrolled dancing leading to madness or death.
So whether you are searching for them to collect for eating, or just to enjoy the wondrous variety of colour, shape, and form, mushrooms are an interesting part of our environment.
Largest organism on earth?
While mushroom caps pop up here and there, the fungal threads of a single organism can spread under the surface of the ground as far as hundreds of kilometers and have a huge mass. The largest on record, according to a 2003 article in the journal Scientific American, is a species of Honey Mushroom, Armillaria ostoyae, growing in Oregon. It covers 2,385 acres and weighs considerably more than a Blue Whale. This particular fungus species has been well studied because it is a pathogen that attacks the roots of live conifers, killing many trees, and yet its fruiting body, being a Honey Mushroom, is edible.
A town in Michigan has a “Fungus Festival” every year using fruiting caps from their humongous, 37 acre, Honey Mushroom as a topping on an equally humongous 8 ft square pizza.