The East Bay Regional Parks District issued an advisory this week about toxic mushrooms in its parks system during the rainy season.
Mushrooms emerge annually after the fall rains, and some contain dangerous toxins. Two of the most toxic mushrooms in the world exist in East Bay parks during the rainy season: the Death Cap (Amanita phalloides) and Western Destroying Angel (Amanita ocreata). They both grow near oak trees and can be lethal to humans and pets, according to East Bay Regional Park District Naturalist Trent Pearce.
The two mushrooms are responsible for most cases of mushroom poisonings in California.
“The Death Cap and Western Destroying Angel mushrooms contain amatoxins, a group of molecules that inhibit cellular metabolism in many animals,” according to the parks district. “In mammals, the liver and kidneys are typically the first organs affected after ingestion. Symptoms don’t usually appear until up to 12 hours after consumption, beginning as severe gastrointestinal distress and progressing to the liver and renal failure if treatment is not sought immediately.”
The district described the Death Cap as 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.” Along with oak trees, it has been found growing with other hardwoods and it is not native to California.
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 disappears with age, and a thin white sac at the base.” It is associated exclusively with oaks, is native to California, and fruits from late winter into spring, officials said.
Deadly toxins can also be found in Galerina and Lepiota mushroom species, which also pop up around the Bay Area.
Park District spokesman Dave Mason advised dog owners to keep a close watch on their dogs during winter months. Pet owners should contact a veterinarian immediately if they suspect their pet ingested a toxic mushroom.
Samson also reminded park users: “Collecting mushrooms in East Bay Regional Parks is not allowed.”
“The Park District urges the public to be safe and be knowledgeable about toxic mushrooms” he said.
On Feb. 3, 2019, the public can learn more about the fungi of the East Bay Regional Parks at the annual Tilden Fungus Fair at Tilden Nature Area’s Environmental Education Center.