Amatoxin-containing mushrooms: Amanita ocreata and A. phalloides in California.

Each year in western North America the greatest number of serious or fatal cases of mushroom poisoning occur in California (5). In the past most of these poisonings have been attributed to Amanita phalloides (Vaill. ex Fr.) Secr., a common species in California. The well known, deadly white Amanitas, such as A. bisporigera Atk., A. verna (Bull. ex Fr.) Pers. ex Vitt. and A. virosa Secr., are not common in western North America and, furthermore, have not been shown to occur in California (2, 9, 17, 19). Over the years fatal cases of mushroom poisoning have been reported in California during the late winter and spring months (1, 3), often after A. phalloides has finished fruiting for the season. A study of the California Amanita flora (2) revealed that only a few species fruit in the spring, two of the most common being A. calyptroderma Atk. &