Lately I've received a number of emails asking me about oyster mushroom identification. The most recent one came in early December from a reader named Tracey. She writes:
Wondering if you could help me. I took photos of mushrooms growing on tree stumps that I had that I could not split and set upright to dry out. This is in Western Pennsylvania a few days ago. Our winter has been very mild so far (40-50 degrees) and damp. Is this the oyster mushroom? And are there mushrooms that could look like this and be poisonous?
Please remember to never eat any mushroom if you're not absolutely sure what it is. The Internet is a great resource, but if you're a beginner you should show your find to a real live expert to be safe. Nothing beats an in person identification!
To read more about these mushrooms in general see this page.
Special thanks to Tracey Ann Miller for the pictures!
Pleurotus ostreatus, is a common edible known for its oyster-shaped cap. One of the first things you should look for when trying to identify this mushroom is the presence of decurrent gills.
Decurrent means that the gills are attached to and run directly down the stem. Take a look at the close up to the right. Can you see how they run into and down the stem?
Other identification features:
White to lilac-gray. It's best to make the spore print on a dark background.
Said to have a mild anise odor, meaning they smell a little sweet like licorice.
Time of year
Summer and fall, or winter as well in warmer areas.
This page tells you how to identify Pleurotus ostreatus, the "true" oyster mushroom. However, there are other mushrooms in the Pleurotus genus that are referred to as oysters. A few examples are:
These species are all edible, so if you mistake a phoenix oyster for a true oyster, you will not be poisoned.
Another similar species is the elm oyster, Hypsizygus ulmarius. This is not a true oyster at all, but is often mistaken for one.
To tell an elm oyster from a true oyster, take a look at the gills. The gills of a true oyster run down the stem, the gills of an elm oyster do not. The elm oyster is edible, although some say not as tasty.
So are there any poisonous look alikes? The poisonous Omphalotus nidiformis is sometimes mistaken for an oyster. It grows in Japan and Australia so become familiar with it if you live in those countries.
The same rules apply here as with any other species. Become familiar with them through reading and pictures, try to find them in the wild, and check your finds with someone who knows in real life. Taking a spore print and checking for gill attachment can be a big help.