Beyond the Soil: Fungi of Coast Live Oak Woodlands
- Busara Firestone
- 2 days ago
- 3 min read
Article and photos by Duncan Keller
NOTE: This post is not a foraging identification guide. Mushroom identification is complex and mistakes can be fatal. Picking mushrooms is also illegal on most Bay Area public land.
Plants and fungi have coexisted on land for at least 400 million years, forming diverse relationships. Today, many fungi are decomposers, while others are parasites. But for many, survival depends on maintaining a mutually beneficial relationship with host plants called mycorrhizal associations– a relationship so ancient, it may have aided the initial transition of plant life from water to land!
Mycorrhiza ("fungus root") extends a plant's root system. The underground fungal web ("mycelium") is made of fine threads ("hyphae") that access areas in the soil where roots can't reach. The fungus delivers water and nutrients to the plant, and in return, the plant sustains the fungus by delivering sugars made through photosynthesis.
My favorite subgroup of mycorrhizal fungi are ectomycorrhizae (ECM). Not only do they specialize in growing with trees, but they produce mushrooms of all shapes, sizes and colors.
A single tree can host many ECM species simultaneously. This explains the changing array of mushrooms in mature woodlands during the "mushroom season" (October-April in the San Francisco Bay Area, depending on the rains). These different mushrooms often link to the same tree(s) because the conditions are suitable for spore dispersal and reproduction. The rest of this post will showcase three ECM fungi associated with coast live oak (Quercus agrifolia), in and around the San Francisco Bay Area.
ECM Fungi of Oak Woodlands (SF Bay Area)
The California Golden Chanterelle (Cantharellus californica) is a flavorful, edible mushroom found in oak woodlands, found near the Santa Clara Valley and usually seen from mid-winter to early spring. However, they are often gritty and hard to clean for culinary purposes. They are known as “mud puppies” as they tend to reach their prime before fully popping up out of the duff.
I first fell in love with mycology (the scientific study of fungi) when I read The Omnivore’s Dilemma (2006), by Michael Pollan. In his journalistic style, Pollan documents a series of food-related adventures, one of which is an outing with a chef to forage chanterelles to serve in his restaurant. It blew my mind that some chefs routinely go into the woods to collect mushrooms for their high-end restaurants.
Santa Cruz County
The Death Cap (Amanita phalloides) is an aptly named mushroom, usually fruiting from late fall through mid-winter in the Bay Area. While it is key for supporting healthy coast live oaks in the region, it is lethally toxic for humans and pets. Ingesting a single mushroom can cause liver or kidney failure. No form of processing - whether boiling, freezing or drying - will make it safe to eat.
This year, California has seen an increase in poisonings, with a recent report citing 40 cases, 4 deaths, and 3 liver transplants. The fungus's presence is not guaranteed near every coast live oak. When it does appear, it's only briefly and under ideal conditions. If curious children or pets are present, scanning the landscape and disposing of mushrooms during fall and winter is advised.
Santa Clara County
The California Satan’s Bolete (Rubroboletus eastwoodiae) is a bizarre-looking mushroom that shows up between late fall and mid winter. Not only are the cap, stem, and pores (spore-producing structures underneath the cap) often a bright red, but the stem of the mushroom can swell bigger than the cap!
For more of a spectacle, slicing the mushroom down the middle reveals flesh that immediately turns a vibrant blue. Though not poisonous in the same way the death cap is, this mushroom is also toxic. It is in the Boletaceae family, along with the prized edible ECM Boletus edulis, also known porcini.
The fascinating world of fungi highlights how complex and interconnected life is in our local oak woodlands. From the tasty chanterelle to the super dangerous death cap, mushrooms put on a vibrant show, reminding us of the hidden biological links that keep our environment going.
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