By Jennifer Vanya, East Bay Regional Park District
Reprinted with permission by the East Bay Regional Park District
Each year, mushrooms come out after the first
rains of the season, which began on November 26.
Mushrooms are ecologically important and can look
beautiful – but some of them contain dangerous toxins.
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.
The death cap and Western destroying angel
mushrooms contain amatoxins, a group of molecules
that inhibit cellular metabolism in many animals.
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.
“Both of these toxic mushrooms can be lethal to
humans and pets if consumed,” said East Bay Regional
Park District Naturalist Trent Pearce, who is based in
Tilden Regional Park and documents the fungi in East
Bay Regional Parks. “They are mostly associated with
oak trees and can be found growing anywhere oak
roots are present.”
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. Though 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.
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 fruits from
late winter into spring. It is associated exclusively