2 Toxic Mushrooms Grow In East Bay Parks

EAST BAY, CA — Mushrooms are an ecologically important part of parklands and can look beautiful, but some contain dangerous toxins, the East Bay Regional Park District cautioned Tuesday.

During the rainy winter season, wild mushrooms pop up in great numbers throughout East Bay Regional Parks. Two of the world's most toxic mushrooms, death cap (Amanita phalloides) and western destroying angel (Amanita ocreata), can both be found in regional parks during the rainy season.

The death cap and western destroying angel mushrooms contain amatoxins, molecules that are deadly to many animals. Symptoms may not appear until up to 12 hours after consumption, beginning as severe gastrointestinal distress and progressing to liver and kidney failure if treatment is not sought immediately.

Both of these mushrooms can be lethal to humans and pets if consumed, the park district said. Pet owners should contact a veterinarian immediately if they suspect their pet may have eaten a toxic mushroom.

The park district reminded the public that collecting any mushrooms in East Bay Regional Parks is illegal.

According to the park district, the best way to stay safe is to ensure that no mushrooms are consumed by humans or pets.

As an added safety measure, community members are encouraged to learn to recognize poisonous mushroom species when encountering them in Regional Parks. Both death cap and western destroying angel mushrooms are mainly associated with oak trees and can be found anywhere oak roots are present.

Death Cap

The death cap is a medium to large mushroom that typically has a greenish-gray cap, white gills, a white ring around the stem, and a large white sac at the base of the stem. Although the death cap is mainly associated with oak trees, it has been found growing with other hardwoods. It was accidentally introduced to North America on the roots of European cork oaks and is now slowly colonizing the West Coast. The death cap is not native to California.

Western Destroying Angel

The western destroying angel is a medium to large mushroom that usually has a creamy white cap, white gills, a white ring around the stem that can disappear with age, and a thin white sac at the base. It fruits from late winter into spring. It is associated exclusively with oaks. Unlike the death cap, it is a native California mushroom.

The park district noted that while the death cap and western destroying angel mushrooms are responsible for most cases of mushroom poisonings in California, deadly toxins can also be found in Galerina and Lepiota mushroom species, which also occur in the Bay Area. See more information about toxic mushrooms.