Thursday, May 13, 2010

LOOK FOR: Oyster Mushrooms

They're not as sexy as morels, nor as predictable, but oyster mushrooms -- Pleurotus ostreatus -- might just be my favorite wild mushroom. And I don't even like oysters.

Photo credit: The Natural Capital
We find oyster mushrooms spring through fall here in the DC area, but they are whitest (and therefore most eye-catching) in the spring and summer. They grow on dead or dying wood, usually on logs that still have their bark. Young caps are about 2 inches across but they can get as wide as 8 inches -- at which point they're a little rubbery for eating.

The stalks of oyster mushrooms are very short, and they don't come out of the middle of the caps. Instead, the stem is off to the side, allowing the mushrooms to grow in overlapping clusters. In fact, their genus name, Pleurotus, comes from the Greek word for side. (And I always thought it was related to the French word for rain!)

Oyster mushroom, pleurotus ostreus, with fungus beetle, triplax thoracica
Oyster mushroom with fungus beetle by the Natural Capital
But one of the most distinguishing characteristics of oyster mushrooms is not a part of the mushroom itself -- it's a little black beetle that we absolutely always find between the gills. They're actually part of a group of beetles known as the Pleasing Fungus Beetles. Triplax lay their eggs on oyster mushrooms, and spend the rest of their lives hanging out among the gills and slowly eating them. They're harmless and easy enough to wash off, and a great identification aid.

Which is important, because there are other similar white mushrooms that grow on wood. They probably won't kill you, but they're supposed to taste awful. Luckily, oyster mushrooms are frequently available at farmers' markets and at high-end grocery stores. You can stop there, or you can use cultivated mushrooms to get a good sense of what they're like there before you go out looking for them (though the ones you see in the store will be relatively dried up after several days of storage, and some farmers select for more colorful strains). Your absolute best bet for safely identifying wild mushrooms is to out with experienced mushroomers, like the ones at the Mycological Association of Washington. (We sometimes find mushrooms on our wild food walks as well.)

Photo credit: Mr Snootyhamper
In the wild: Like many mushrooms, oysters like shade, and they clearly respond to rain -- you'll often see them a day or two after a good soaking. Keep an eye out when you pass downed logs. Once you do find some, they'll come back in the same location repeatedly.

In your yard (or apartment): Oyster mushrooms can be cultivated on many different substrates that contain cellulose -- not just logs but also shredded paper, coffee grounds, or sawdust. There are even kits using rolls of toilet paper as the base, designed to grow indoors. If you want to give it a try, check out the products at Field & Forest or Fungi Perfecti.


Gene Koo said...

Is it legal to harvest wild mushrooms? And even if it is, do you recommend it (will it have a negative impact on habitats)

Elizabeth | The Natural Capital said...

Good questions Gene. For legality it depends on where you are. It's definitely not legal in national parks. But MD state parks do allow limited mushroom picking (and berry picking) -

“Lt. Col. Chris Bushman, deputy superintendent of the Maryland Park Service said it is OK to collect mushrooms in state parks for personal consumption only — but when in doubt, ask. ‘There is a regulation that prevents a person from removing anything from a state park’ but it is waived for things like collecting mushrooms and berries for personal consumption. Collection of all mushrooms is limited to a half gallon per person per day at Catoctin Mountain Park.”

Not sure about VA. I just checked the Montgomery County parks rules and as far as I can tell they're silent on fungi.

As for habitat, if you pick the mushrooms carefully you're not harming the overall organism -- you're picking the fruiting bodies of something that has mycelium running through whatever wood or soil it's growing on. We usually try to leave some behind to make sure the organism does get to reproduce. I haven't heard anyone expressing concerns that the mushroom population is in decline due to picking.

Michael Carnahan said...

Can you please tell me which varieties of mushrooms are most abundant in Maryland State Parks? In other words, if I go to a park to hunt for mushrooms, what should I be looking for, or what might I be most likely to find? Thanks!!!

Elizabeth | The Natural Capital said...

Michael, it really depends a lot on the weather and the time of year. Last week we were seeing a lot of boletes and amanitas. I really recommend heading out on a foray with the Mycological Association of Washington -- they'll get you off to a good start.

Elizabeth | The Natural Capital said...

Just found oyster mushrooms on December 4 -- I think this is the latest we've ever found them!

montreal home inspector said...

I love foods with oyster mushrooms specially oyster pasta and grilled oyster mushroom . Anyway , we have oyster mushroom cultivation in our home .

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