As humans, we have an innate attraction to nature. A childlike curiosity. But beware
of what you find in the shadows.
In Northern California, something deadly is popping up in the forest.
This poisonous mushroom is known as the "death cap."
Donna Davis: The forest was just damp. Perfect.
Donna Davis went collecting mushrooms one day in 2014.
Donna: It's very magical when you're there. It really is quite like a treasure hunt.
I felt confident enough that I knew what I was doing.
But she didn't recognize the telltale cup-shaped
tissue that grows on the bottom of the deadly mushroom.
And she mistook young, egg-shaped death caps for something she could eat.
Donna: And I made mushroom soup. It was amazingly delicious.
One cap has enough toxin to kill a human being.
Donna: The next morning I felt really tired and I took a little nap.
For the first six to 12 hours you feel OK.
But meanwhile, the toxin is quietly destroying your liver cells.
Donna: The next thing I knew I was in emergency care.
Death caps spread the same way other mushrooms do.
Just like this harmless oyster mushroom, a death cap shoots hundreds of thousands of
spores into the air.
The spores drift into the shadow of California live oaks, where they grow filaments that
attach to the trees' roots. Each fungus filament is about the width of a human hair.
Under the microscope, you can see how the white fungus envelops the tree's pink root
tips. This is called a mycorrhizal relationship.
The fungus feeds on the trees' sugars and gives it nutrients in exchange. It's good
for the fungus and for the tree.
And that's how the death cap snuck into California
from Europe on the roots of a decorative shrub, in the 1930s.
Researchers aren't sure why the death cap has evolved to be so lethal.
What exactly is it protecting itself from?
Humans -- we're just collateral damage in some battle that we don't understand.
Scientists like Anne Pringle, from the University of Wisconsin, are doing genetic testing on
death caps to see how long they live.
If death caps have a short lifespan, it might be enough to pluck them from the ground so
the spores can't spread. Less opportunity for people to eat them.
Donna: I remember closing my eyes and seeing like this beautiful path. And all of a sudden everything
got really dark. And I thought, "Oh, I'm not supposed to go down this path."
Donna survived. But death caps killed two people in California that year.
Donna: It is really brutal. Nature has its own rules.
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