Edible and poisonous mushrooms of Canada

INTRODUCTION
form and color, the great number of species that occur, and their interesting
relationships with other plants and types of habitat are all features that invite
further study.
One of the things that adds to the interest of mushroom collecting is the
fact that one may visit the same locahty time after time and continue to find
different species. Some of the common ones will be found repeatedly of course,
but something different is likely to be found at any time under varying weather
conditions. Some species seem to produce fruiting bodies only rarely, perhaps
only once in several years, so that there is always the possibility of coming
upon a rare and unusual species, even on famihar ground.
Mushrooms are also interesting from the standpoint of their place in the
economy of nature. One of their chief functions is to aid in the breakdown of
dead organic material and to return the essential elements to the soil. When
this function is appreciated, their frequent association with decay is understood
and any feeling of repulsion toward them disappears. Some of the species are
found only with certain trees where they form associations with the tree roots
that are termed 'mycorrhiza.' Some trees cannot thrive without the presence of
their fungus associate. Attention has also been directed in recent years to the
mushrooms as a possible source of antibiotic substances that might prove
useful in medicine. Investigations are being carried out to see if the hallucino-
genic mushrooms of Mexico might prove to be a source of a non-habit-
forming tranquilizing drug that would be valuable in neuropsychiatric re-
search. Investigation of the mushrooms from these and similar angles is only
beginning.
It should be realized that in our mushroom flora we have many more
species that must be omitted from a book of this nature than can be included.
Consequently, caution must be exercised in making identifications. If the
characters of a particular specimen under examination do not agree in all
respects with the description, there is a good chance that the mushroom may
be a species not in the book, hence for safety's sake it should not be eaten.
PARTS OF A MUSHROOM
Most people have a general idea of what a mushroom is, but the term has
never been precisely defined and has diff^erent meanings to different people.
Perhaps the most generally accepted usage is to apply the term mushroom to a
fungus fruiting body with a more or less evident stalk, bearing an expanded
cap at the apex, with a series of thin, radiating, gill-like or blade-Hke structures
on the lower surface of the cap. Some would consider that only one or two
species such as the meadow mushroom and cultivated mushroom are true
mushrooms, whereas others would call almost any large fleshy fungus a mushroom.
From a scientific standpoint it is probably best to use the term mushroom
to apply to the whole group of gill-bearing fungi and it is used in that sense in
this book.