2 Of World's Most Toxic Mushrooms Found In East Bay Parks

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

"With the return of winter rains, park visitors may have noticed mushrooms popping up in the Regional Parks," Park Spokesperson Dave Mason said. "The death cap (Amanita phalloides) and western destroying angel (Amanita ocreata) are two of the world’s most toxic mushrooms, and both can be found in East Bay regional parks during the rainy season."

Both mushrooms contain amatoxins, which are deadly to many animals and can be lethal to humans as well. Both mushrooms are also mainly associated with oak trees and can be found anywhere oak roots are present, Mason said.

Death Cap

According to the park district, the death cap is a medium- to large-sized 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 also a medium- to large-sized mushroom. It 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.

But Wait, There Are More

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. For more information about toxic mushrooms, visit Ebparks.org/safety/trails/toxic-mushrooms.

What To Do

Collecting any mushrooms in East Bay Regional Parks is not allowed so please refrain from it.

Keep pets on leash. Any pet owners who suspect their pet may have eaten a toxic mushroom should contact a veterinarian immediately.

Inform Yourself

Not all mushrooms are bad. The Tilden Fungus Fair runs Jan. 20-21 and is a great way to celebrate and learn more about the fruits of winter.

In addition to viewing hundreds of local mushroom specimens on display, guests can mingle with the mycological community and see presentations by guest speakers at this two-day special event held at the Tilden Nature Area, 1500 Central Park Drive in Berkeley.

The event runs from 10 a.m. to 4:30 p.m. Saturday and Sunday, Jan. 20-21. This is a free event and there is no pre-registration; it is a drop-in event only. Go to Ebparks.org/events/tilden-fungus-fair for more info.