Toxic Fungi of Western North America

by Thomas J. Duffy, MD

General description and occurrence

The genus Psilocybe has a variety of cap configurations, sometimes with an obtuse or acute umbo, but rarely with much of a central depression. The caps are usually ± brown; typically viscid, smooth and fading to ochre or yellow brown with drying. Caps and stipe are not particularly fragile and some viscid caps have the upper gelatinous layer separable. The gills are attached to the stipe. The spore print is typically dark purple brown. Species with a high amount of active indoles usually bruise blue or blue-green. The genus Psilocybe occurs in a variety of habitats including wood chips, but never on living or dead trees.

(In the following lists of species for Western North America, those Psilocybe species also found in Mexico are underlined.)

Active species of Psilocybe known to occur in California include Psilocybe aeruginosa (Curtis:Fr.) Noordeloos [=Stropharia aeruginosa (Curtis: Fr.) Quélet], Psilocybe azurescens, Psilocybe baeocystis, Psilocybe caerulescens {but almost certainly imported from central Mexico}, Psilocybe caerulipes (?), Psilocybe cyanescens [San Francisco to Alaska], Psilocybe cyanofibrillosa, Psilocybe inquilina (Fr. ex Fr.) Bresadola, Psilocybe mairei, Psilocybe merdaria, Psilocybe pelliculosa, Psilocybe physaloides (Bull. ex. Merat) Quélet [Santa Barbara to Alaska], Psilocybe semilanceata, Psilocybe squamosa and Psilocybe subaeruginascens. (166,167,168,169) The citations are from Paul Stamet’s Psilocybin Mushrooms of the World. (167) The material labeled Psilocybe caerulipes (Peck) Saccardo in San Francisco State's Harry D. Thiers Herbarium from Golden State Park may be an undescribed species or variety as the spores are longer (up to 11µm) than those described by Singer and Smith in 1958. (170) Additionally, Psilocybe caerulipes has an Eastern U.S. distribution. Dr. Guzman made two collections of what he called Psilocybe caerulipes in Mexico (167) and those collections should be compared with the California material and with the Eastern Psilocybe caerulipes.


Psilocybe cyanescens photo © Fred Stevens

The PNW has additional Psilocybe species: Psilocybe caerulea (Kriesel) Noordeloos [=Stropharia caerulea Kriesel], Psilocybe fimetaria (Orton) Watling [=Stropharia fimetaria Orton], Psilocybe liniformans var. americana, Psilocybe luteonitens (Peck) Saccardo [=Stropharia umbonatescens (Peck) Saccardo], Psilocybe moellerii, Psilocybe montana, Psilocybe pseudocyanea (Desmazieres: Fr.) Noordeloos [=Stropharia pseudocyanea (Desmazieres) Morgan], Psilocybe silvatica, Psilocybe strictipes Singer and Smith, Psilocybe stunzii Guzmán and Ott and Psilocybe subfimetaria. (171) Most of these taxa occur in British Columbia in addition to the reported Psilocybe baeocystis, cyanescens, semilanceata, strictipes and stuntzii. (167) Psilocybe physaloides (Bull. ex. Merat) Quélet) has a stupendous range from Santa Barbara to Alaska.

Many more psilocybe species probably occur only in Mexico, the gulf states and Middle America. These include two collections of Psilocybe caerulipes (a primarily Eastern US species), Psilocybe herrerae, Psilocybe hoogshagenii Heim sensu lato, Psilocybe jacobsii, Psilocybe mammillata, Psilocybe muliericula, Psilocybe pelliculosa (Smith) Singer and Smith. Those species favored by the shamans of Oaxaca are Psilocybe aztecorum, Psilocybe caerulescens, Psilocybe mexicana and Psilocybe zapotecorum. The shamans also use raw Lycoperdon mixtecorum and Lycoperdon marginatum in some areas of Mexico. Their use in these rites apparently is symbolic as these puffballs have no hallucinogenic effects. (178a)

The genus Panaeolus typically has a ± white, yellow-brown or brown cap, often ± conic or bell-shaped, viscid or dry, occasionally with remnants of a partial veil at the edges. A separable surface layer is not present. The pallid gills are attached to the stipe and typically are mottled black with the dark spores, because the spores do not all mature at the same time and the immature spores contain little pigment. A ring may be present.

Western North America has 1-2 active species of PanaeolusPanaeolus subbalteatus and one possibly active species—Panaeolus semiovatus. (167,166) Other species such as Panaeolus castaneifolius, Panaeolus fimicola and possibly Panaeolina foenisecii (= Panaeolus foenisecii) are latently hallucinogenic. Stamets notes that a form of the latter, which occasionally bruises blue, has been found in the grassy coastal areas of California and may be a new species. (166)

Inocybe aeruginascens, which bruises blue at the base, is widely distributed in western America and is weakly active. Two possibly hallucinogenic, but quite small, Conocybes have been reported in the West: Conocybe cyanopus (Washington, Colorado, British Columbia) and Conocybe smithii (Oregon and Washington). The base, or at least the mycelia just below the stipe, blue in these species. These mushrooms are similar to other Conocybe species that contain amanitins. Hypholoma (Naemataloma) popperianum is the only indole-containing Hypholoma and there is only one voucher specimen from Western North America (Golden Gate Park in San Francisco). (172)

The genus Gymnopilus has a rusty brown spore print and is usually found on wood. The caps are usually dry and are often brightly colored. A partial veil is often present and varies from web-like to fibrillose. Psilocybin was found initially in five species: Gymnopilus luteus, G. spectabilis, G. validipes, G. aeruginosus and G. viridans. (173) Gymnopilus spectabilis is a common large bright orange mushroom found clumped on logs or stumps in the west, but it does not appear to be toxic as the eastern mushrooms are. Paul Stamets and others have noted that this species with a stipe usually 1-6 cm wide is easily confused with Gymnopolis ventricosus, which is known to be hallucinogenic. This species has a wider swollen stalk and very shallow gills. (166) Active species in California and in the PNW are Gymnopilus aeruginosus with its dull blue-green or mottled blue-green cap when young and Gymnopilus luteofolius with its somewhat purplish scales and its thick reddish to purplish flesh when young. Warning: at least one species of Gymnopilus in Austria may contain amatoxins, Gymnopilus spadiceus (Singer, 4th edition Agaricales). No amatoxin-containing species of Gymnopilus have been found on this continent.

Gymnopilus spectabilis
Gymnopilus spectabilis photo © Michael Wood

Gymnopilus luteofolius
Gymnopilus luteofolius photo © Michael Wood

Cortinarius infractus, a common species found in temperate zones, contains indole alkaloids. (174) Conocybe cyanopus and Conocybe smithii are found in the PNW and may occur in Northern California. The basal mycelia stain blue when handled.

Stropharia coronilla, an edible mushroom that occurs in the West, presumably caused 2 bizarre Arkansas poisonings in 1976. Two healthy young visitors from Iowa made a soup from fresh Stropharia coronilla. About an hour later malaise, severe headache, generalized aching, flushing, incoordination, muscular weakness, difficulty walking and confusion occurred in addition to GI symptoms. Both victims had hallucinations and delirium. One had fever and one lost consciousness. Even the following day they had headache and bone pain. (175)

The University of Arkansas identified specimens from the collecting areas as Stropharia coronilla. Photos were sent to Dr. Barry Rumack at the Rocky Mountain Poison Control Center in Denver where both he and Dr. A.H. Mitchell agreed on the identification as best as that could be done without actual material. Although Arkansas locals did look for blue staining Psilocybes under cow pies, the two visitors insisted they had not done so. Some of their symptoms, such as severe headache, flushing and bone pain were not psilocybin symptoms. Another toxin or possibly a chemical contaminant appears to have been present.

Pluteus salacinus occurs along the California coast and in other areas of the West. Like the genus Psilocybe, it contains psilocybin, but recreational use is probably rare. (8) Its smooth spores are pink in mass.

A few US polypores are stimulants or mild hallucinogens. Phaeolus schweinitzii is the most common species. Since it is woody, about the only way it can be used is as a bitter herbal tea. The psychotropic agents may be hispidin and bis-noryangonin. These compounds are also found in kava-kava, a pleasant tasting tea greatly appreciated in Indonesia. Hordenine and probably tyramine & N-methyltyramine are found in two polypores: Bondarzewia berkeleyi and Bondarzewia montanus. Possession of kava-kava is legal in the United States and is only mildly stimulating.

Laetiporussulphureus” produced hallucinations in a six year old child, after she had nibbled away at a sulfur shelf. (176) The MSSF Toxicology Committee Survey in 1975 reported one ingestion in which an adult had a tingling sensation in the fingers, a floating sensation, some dizziness and a feeling of disorientation. (177) Western collections of Laetiporus sulphureus contain hordenine, tyramine, N-methyltyramine and two unidentified alkaloids. (178) We now know that Western North American Laetiporus “sulphureus” is actually 2 or more different species. The Laetiporus that grows on Eucalyptus and probably on oaks is Laetiporus gilbertsonii. (188a) The Laetiporus growing on conifers is Laetiporus conifericola.

In the Yukon Territory, the native residents chew a polypore found on birch trees—Phellinus igniarius. The tough mushroom is burned to an ash and mixed with chewing tobacco and tea leaves. There is only a sedative effect, but first-time users may experience a mild headache. (179)

Occasionally, other fungi produce unexpected hallucinogenic effects. For example, Hygrocybe (Hygrophorus) punicea was reported in one California case to have caused GI symptoms with hallucinations and disorientation. Other people, who have eaten this species, have not noted any CNS toxicity. Such isolated reports of toxicity require confirmation of the species involved. They do serve to remind us that little is known of the taxonomy or possible toxicity of many fungi or of the idiosyncratic ways in which particular victims may react. (177)