Wild oyster mushrooms.

Why this species is interesting here

Almost everything worth foraging in Colorado is at 9,000 feet. Wild oysters are the exception: they grow on dead and dying hardwood at Front Range elevation — cottonwood along creek bottoms in Longmont, Boulder and Denver, plus aspen higher up and willow in the right places.

It is also the same species, Pleurotus ostreatus, that we grow in the fruiting rooms. Which makes it the one case where you can directly compare a wild find with the cultivated version — and the honest answer is that they taste very similar, with the wild one usually tougher and more insect-damaged.

Identification

• Growing on wood — dead or dying hardwood trunks, stumps and fallen logs, in shelving, overlapping clusters. Never on the ground.
• Cap: shell- or fan-shaped, white to grey to tan, smooth, two to eight inches across.
• Gills that run down the stem (decurrent) — white and widely spaced, continuing onto whatever short off-centre stem exists.
• Stem: short, off-centre, or absent entirely.
• Flesh: white and firm.
• Smell: pleasant and faintly anise or almond.
• Spore print: white to pale lilac.

On wood, fan-shaped, white decurrent gills, off-centre or no stem, anise smell. Anything growing from soil is not an oyster mushroom, whatever it looks like.

What to check against

Oyster mushrooms are among the safer wild species to learn because the combination of wood-growing habit, shelving clusters and decurrent white gills is distinctive. Still:

• Anything from the ground: stop. This rules out most dangerous gilled mushrooms in one move.
• Orange, clustered, on wood, with sharp non-decurrent gills: possibly Omphalotus (jack-o’-lantern) — toxic. Colour and gill attachment separate them.
• Small brown mushrooms on wood: never assume. Galerina marginata grows on wood and is deadly — but it is brown, small, has a ring on the stem and a brown spore print, and looks nothing like an oyster to anyone paying attention. Read dangerous lookalikes.
• Bitter or acrid taste: several wood-growing species are inedible from bitterness rather than toxicity.

Season and condition

Spring and autumn, after rain, with autumn generally better along the Front Range. Cool wet weather produces the best specimens. Check for insects — wild oysters are frequently full of beetle larvae, particularly in warm weather. Young, firm, small clusters are worth taking; large soft shelves usually are not.

Cooking, and the honest comparison

Treat them exactly as you would cultivated oysters: tear rather than slice, hot dry pan first, fat second. All thirty of our recipes apply directly, and the blue oyster page is the relevant species reference.

Where wild differs: tougher flesh, more variation between specimens, more waste from insect damage, and shorter usable life because you rarely find them on day one of their fruiting. Cultivated oysters are cut at the ideal moment; a wild one has been out in the weather for an unknown number of days.

Common questions