When the rains began this October mushrooms started popping up almost immediately.

First, I noticed a few near the red maple in my front lawn, then other interesting ones at various locations.

One of the coolest is the Dead Man’s Foot. I spotted this one at several locations in barren, compacted soil, not far from trees. Irregular, grayish and rough in shape, one can imagine it as a decomposing foot pushing up out of the ground. Appropriately, right around Halloween this year.

It grows with such force it can lift patio paving stones and bricks.

Described in David Arora’s wonderful little book “All That the Rain Promises and More,” it is Pisolithus tinctorius and listed with various common names: Dyemaker’s False Puffball, Stone Puffball, and Bohemian Truffle. I love that last one. Sounds like a Central European folk dance.

This odd mushroom is one of many that extract minerals and moisture from the soil and trade them off with plant roots in exchange for carbohydrates, which fungi cannot generate on their own. In this symbiotic relationship, the fungus and the plant join to form organs called mycorrhizae: “myco” means fungus, and “rhizae” means roots.

It is a relationship that most plants must have to survive. And one that is commonly employed commercially. P. tinctorius is included in many fertilizers and soil inoculants.

A few years after I had to remove the dying white birch trees from our front lawn, massive clusters of mushrooms began to appear with the onset of autumn rainfall. Now, many years later, they have not returned. Most likely, the fungus has digested the dead roots and no longer obtains enough food to support the formation of mushrooms.

Fungi need “carbs” to live. But not being animals that can eat food, nor plants that produce their own carbs by photosynthesis, fungi are great at absorbing water, extracting minerals from soil and using carbohydrates generated by plants and trees.

With respect to trees, most fungi are innocuous or beneficial, but a few are of serious concern.

A good example is another mushroom that tends to appear during our rainy season, usually in December: Honey mushrooms, clusters of honey-gold, gilled mushrooms appearing at the base of the trunk or on surface roots of trees colonized by Armillaria, commonly known as shoestring rot or oak root fungus.

Armillaria exists as various species and strains that vary in aggressiveness as plant diseases and wood-decay fungi. They grow in temperate climate zones all over the world, living on woody plant parts, mostly below the soil surface.

Doing root collar exams on oaks, I’ve often observed Armillaria living as small, inconspicuous lesions on below ground bark surfaces, doing no apparent harm.

Oaks are resistant to it, but they become susceptible when conditions favor disease: older trees in declining health and subjected to wet root zone conditions in summer. As the disease progress, the fungus digests living cambial zone tissue as well as the wood in the lower trunk and roots.

That is one example of many fungi that cause disease or decay in trees in the Napa region and similar climate zones.

Doing a quick review, and for today ignoring the numerous fungi that cause leaf and branch diseases and do not form mushrooms or mushroom-like structures, I counted 13 other Genera of fungi with which the diligent arborist should be familiar in our region. Some of the common names for these include oyster mushroom, charcoal fungus, artist’s conk, red ring rot, velvet top fungus, hedgehog fungus, sulfur fungus, weeping conk and split gill fungus.

Some produce ephemeral, soft mushroom-like structures while others grow perennial, or “woody” fruiting bodies, also known as sporophores, basidiocarps and “conks.”

Some are edible, some poisonous, and some hard as wood.

When we see the fruiting bodies on trunks, limbs or root collars, we need to be aware that the fungus has absorbed enough food from the host to “mature” and reproduce. That can mean the wood is gone and the tree might be ready to fall over.

In a large tree, this can indicate a risky situation.

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In the big picture of life on Earth, we have six kingdoms:

Archaebacteria: single cell bacteria that live in extreme conditions, like deep ocean thermal vents.

Eubacteria, the common, single cell bacteria.

Protists: slime molds, algae and various organisms that do not fit into the other categories.

Plants: Our friends that produce carbs via photosynthesis.

Animals, including people.


I’ve heard it said that plants were able to colonize the land only with the help of fungi.

Where would we be without them?

Bill Pramuk is a registered consulting arborist. Visit his website www.billpramuk.com, email questions to info@billpramik.com or call him at 707-226-2884.