Toxic Fungi of Western North America

by Thomas J. Duffy, MD

Introduction and collection of specimens

Since the 1977 publication of “California Toxic Fungi”(1), there have been numerous journal additions, more information on the fungi of western Canada and much more interest in the mushroom flora of Mexico. Toxic Fungi of Western North America covers this larger area (from Alaska through Mexico and from the Pacific Ocean through the Rocky Mountains) and includes additional information, especially on new categories of mushroom poisoning. However, except for liver transplantation and much better intensive care treatment, there have been few major breakthroughs in therapy.

CA Toxic Fungi

The guide below is based on clinical experience and reviews of North American and European references. The final determination of safety, however, has to be made by each collector, as does the specific treatment of individual patients by physicians. Many treatments, especially in Slavic countries (which have the most experience) are lacking in statistical significance, often routinely selecting and/or reporting on 100 or fewer samples.

Mushroom names are the scientific ones, which consist of a genus name, a noun, which is capitalized and a species epithet, an adjectival form which is not capitalized. Both are italicized. They indicate one and only one species and place it firmly in a family of names. This report avoids common names, which vary from one area to another and often refer to more than one fungus. For a more detailed examination of scientific names see the two addenda to this paper, which review in particular names in the genus Amanita.

In poisoning cases, any mushroom leftovers should accompany the patient for identification. Wax paper serves well as it allows the mushroom to “breathe”. Decay in a plastic bag may render a specimen unidentifiable even for an experienced microscopist. A timely trip to the same area from which the offending mushrooms were collected may allow gathering of additional material, which should include the extreme base of mushrooms to check for universal veil tissue left in that area. That so-called “death cup” or volva may be reduced to thin membranous limbs arising from the upper part of the stalk’s bulbous base and often collapsed on it. [see glossary for “limb”] Sometimes the volva leaves only ragged rings of tissue on the lower stalk or even presents as friable flakes that may be left in the soil when specimens are excavated. The universal veil enfolds species when they are young and often leaves tissue on the cap as well.