Fun Times With Fungi

By Constance Taylor

Show of hands… who knows that Lake Merritt is home to a wide variety of fungi?

One person who does is Damon Tighe, walk leader for our December 15 Mushrooms of Lake Merritt walk.  Damon is an amateur mycologist of five years and a former research scientist at the Joint Genome Institute, where many fungal genomes have been sequenced for biofuel applications.

A stalwart group of fungophiles showed up despite cloudy skies and insistent drizzle to learn about the mycology around our fair urban slough.

Damon started by going over some mycological basics and interesting facts-

  • The majority of a fungi’s life span is spent as a single cell mat with occasional fruiting bodies (mushrooms).  The largest mat recorded to-date is 15 km, or 7.5 miles, across!
  • There are generally two types of mushrooms: michorrhizal, which is often associated with their symbiotic relationship to roots in helping fix nitrogen, and saprotrophic, the type of fungus that feeds off decaying matter.
  • Fungal genomes are much larger than those of humans
  • Fungi are the predominant vehicle in our world to help cycle carbon and nitrogen in the environment.
  • You can find mushrooms by reading the landscape for them- for example, mushrooms often grow at the bottom of sloping land.  Any available water will run downhill, which helps keep mycelium mats moist year-round.
  • Oyster mushrooms are one of the fungi that have an industrial use.  After an oil spill, oyster mushroom spores are sprayed onto the slick- as they grow, they absorb the toxins which are then dispersed by the animals that eat the mushrooms.  The animals don’t eat enough of the toxins to be harmed, and the pollutants are diluted from the area of the spill.
  • Any mushroom is safe to handle, including the epically named Death Cap and Destroying Angel, the two deadliest mushrooms in California.  This is because the toxins are confined inside the cell walls, and the cell walls of mushrooms are made of chitin, the same stuff that insect exoskeletons are made of.  It’s very tough and won’t break apart just by handling- theoretically you can even chew a poisonous mushroom and spit it out without getting sick because the cell walls only break down once they’re exposed to your stomach acid. But we don’t recommend trying it- there are better ways to impress your friends!
  • When you’re picking mushrooms it’s best to cut them at the base with a knife versus plucking them out of the ground.  Cutting prevents the mycelium mat underneath from being damaged.
  • There are three general things to look for when identifying mushrooms:
    • Morphology: What is the shape, structure, and color?
    • Color of Spores (Sporeprint): Take a white piece of paper and gently press the cap onto it gill side down.  The spores will make a starburst pattern with a color that varies from species to species
    • Scent: Take a whiff.  Does it smell lake maple syrup?  Cabbage farts?  Add that bit of information to your species detection clues.

And now may we present… (drumroll)… the mushrooms of Lake Merritt!

Click on the images to make them larger

Honey mushroom


Honey mushroom (Armillaria mellea): You can usually find large clusters growing on rotting wood.  The honey mushroom is also the largest living thing on earth!  It’s the 15 km michorrhizal mat mentioned above.



The different morphologies of a Death Cap

Death Cap (Amanita pholloides): The immature death cap looks very similar to the edible puffball.  To tell the difference, cut the mushroom in half- the death cap will have the beginnings of a cap and gills on the inside, wheras the puffball will not.  Death caps, a michorrhizal mushroom, tend to grow near oak trees where they help the roots fix nitrogen.


Immature Death Cap cut open- you can see the gill structures starting to form

Meadow Mushroom (Agaricus campestris): These edible mushrooms tend to get eaten by slugs as soon as they pop up.  The skin stains pink when bruised.  One way to tell an edible mushroom from a poisonous one is that bugs will have eaten the edible ones, and the toxic ones will be pristine.

A fairy ring of Yellow Stainers

Yellow Stainer (Agaricux xanthodermis): Very similar looking to the meadow mushroom, but toxic.  These mushrooms stain yellow when bruised.

Jack O' Lantern mushroom

Jack’o’Lantern mushroom (Omphalotus olearius): A bioluminescent mushroom!  Insects are attracted to the glow, which is how it spreads its spores.  The light isn’t bright enough to see with the naked eye, but put a time-lapse camera on it at night and you’ll see it glow.  It’s often mistaken for a chanterelle, as they’re both the same color and have very similar structures.  You can find this mushroom in large patches usually growing on decaying plant matter.

Pleated Inky Cap

Pleated Inky Cap (Coprinus plicatillis): These mushrooms pop up the day after a rain and break down very quickly after.  They’re edible but they inhibit your ability to break down alcohol, so if you drink some booze with your Pleated Inky Cap dinner be prepared for vomiting and an uncomfortably fast heartbeat.



Blewit (Clitocybe nuda): An edible mushroom that grows in leafy matter and is bright blue when it first comes up.  Some people like to colonize their compost bins with these mushrooms for the dinner table.

Bearded Milk Cap (Lactarius pubescens): Leaks a milky latex when the gills are sliced.



Shaggy Parasol with yellow oxidation on stem after being cut

Shaggy Parasol (Lepiota rachodes): A saprotrophic mushroom that’s often found growing on piles of forgotten wood chips.  The stem starts oxidizing to a bright yellow immediately after it’s cut.  It’s edible, but some people have violent stomach reactions.

Stropharia riparia: Can be used as a garden pest preventer because it contains a crystal structure that slices into worms and maggots.  Not good to eat!


Cabbage Parachute (Gymnopus brassicolens)

Cabbage Parachute

Mature Lattice Stinkhorn

Latticed Stinkhorn (Clathrus ruber): Definitely the oddest-looking of them all.  This stinky mushroom has an open lattice structure to allow flies in.  As they’re crawling around inside, the black spore-containing goop sticks to them, which is how this mushroom spreads.

Immature Lattice Stinkhorn cut in half

Other mushrooms spotted during the day were the Wine colored agaricus (Agaricus subrutilescens), Stropharia ambigua, Russula basifurcata, Wavy cap (Psilocybe cyanescens), and the Red Lead Round Head Mushroom (Leratiomyces ceres)

For more information you can check out Damon’s photos of Oakland mushrooms at the link below.  If you type “mushroom oakland” into the tags you’ll get a visual list of all that goes on fungally in Oakland.

The other BIG resource for budding mycologists is the “Simple Key” from Mykowebs California page:

A big thanks to Damon for leading an excellent walk!  Be sure to catch him again for his February 9 “Nature Photography Basics” walk.

See you there!

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