For those of us who venture out into the parks on these cool, rainy winter days, nature is rewarding us with a great variety of mushrooms to observe.  One that is out in great abundance right now is Amanita phalloides, also known as the Death Cap.  Because  of the heavy rainfall in October, these mushrooms can now be  seen in great profusion in  many parks in Oakland and Berkeley, including Tilden Park and Joaquin Miller.

Amanita phalloides is a member of the Amanita group of mushrooms that contains not only some of the most beautiful and delicious  of all mushrooms, but also some of the most poisonous.  While they are interesting to observe, the poisonous ones are deadly to ingest. The Death Cap and her cousin, the Destroying Angel, Amanita ocreata, are the two most poisonous mushrooms known and are the culprit for most all mushroom related deaths. They both contain phallotoxins  and amanitins , substances that prevent protein synthesis in the cells.  These toxins affect all the organs to some degree, but severely  effect the liver and kidneys.  The mushrooms are said to taste pleasant, and symptoms generally don’t begin until 8-12 hours after ingestion, during which time, great and irreversible damage has already been done.  One need only consume a single mushroom to have a deadly reaction.

Without  treatment, a person would die within 1-2 weeks.  There is no antidote to the toxins; however, some treatments are known to be effective if administered quickly enough.  Penecillin  G and Silibinin,  made from Milk Thistle  have been known to have some effect.  Ultimately, a liver transplant would be the only real solution--but avoiding them is a much easier way to go!

Fortunately, the amanita group all have a few common denominators that help in identification.  Amanita all have pale colored gills  and white spores; and most importantly, are all initially enveloped in what is called  a ‘universal veil’.  This universal veil ruptures as the mushroom matures and tends to leave some remnant of tissue on the cap and a distinct sac, or volva, at the base of the mushroom.  This sac is not readily seen and often one must remove some dirt or leaf litter in order  to observe it.  It is the telltale  signature however and one must be very careful to dig the mushroom up in order to ID it properly. 

A. phalloides  and A. ocreata are both abundant under oaks, particulary Coast Live Oak, but the Death Cap tends to fruit in early to mid winter and the Destroying Angel tends to fruit in the spring.  The Death Cap has a yellow-green cap that can have a metallic tinge to it when dry.  In contrast, the Destroying Angel is usually pure white. 

The deadly Amanita mushrooms are often accidentally eaten by immigrants in whose homelands there are no deadly look-alikes .   They are often mistaken for the Straw Mushroom or a Puff Ball.  These cases of mistaken identity could easily be prevented by checking for the volva or dissecting the mushroom at its egg stage to discern whether or not it is solid.  A  dissected Puff Ball will appear solid and an Amanita egg will show a distinct ‘embryo’ outline.  

Whereas humans can, with some training, discern between a poisonous mushroom and an edible one, dogs have been known to eat them  outright, perhaps because they tend to smell sweet. This season has already seen a particularly high number of amanita related dog deaths. If you like to take your dog in the woods with you, be especially alert to what your dog may be eating. In fact, it's safer to keep them on leash when hiking in parks where these mushrooms occur.  After all, you want to ensure the safety of your pet while out enjoying  a nature walk during this abundant mushroom season.

Take action:

If you'd like to read more about Amanita, here are some links:

• MyKoWeb, site devoted to the science of mycology (the study of the fungi) and the hobby of mushrooming (the pursuit of mushrooms)
• Bay Area Mycological Society
• Mycological Society of San Francisco

To see--but hopefully not ingest--Amanita in the Oakland parks, visit just about any park these days but check out

• Joaquin Miller off highway 13
• Leona Canyon off the Merritt Campus

About Morgan Evans

When Morgan Evans isn't studying at Merritt in the Ranger/Naturalist Program she might be found acting as an Interpretive Student Aide at the Tilden Nature Area, EBRPD. In her down time she leads local hikes for the Sierra Club, (when it doesn't conflict with her backpacking). A voracious mushroomer and forager for all wild edibles, she's a graduate of the CA Culinary Academy, and caters private parties for individuals.