Oyster mushroom

oyster mushroom

Ali Mckernan

Oyster mushroom

Scientific name: Pleurotus ostreatus
Oyster mushrooms are shell shaped fungi that grow in tiers or fabulous clusters on dead trees or stumps. Unlike many fungi, these mushrooms are not seasonal and can be found all year round, especially after a cold snap which can trigger the fungus into fruiting.

Species information


Average cap diameter: 5 - 15cm (occasionally even larger)
Average stem length: 1 - 4cm

Conservation status


When to see

All year round


These beautiful shell like mushrooms grow horizontally out of the dead and dying wood of deciduous trees, especially beech. They are a saprobe, which means they live off decaying organic matter, and are specialists in breaking down some of nature's toughest materials - cellulose and lignin. In the process, they release vital nutrients back into the ecosystem.

How to identify

This oyster starts out a beautiful grey blue colour with a cap edge that rolls slightly inward, gradually opening out turning grey brown and wavy with age. Look underneath, and you'll find they have crowded whitish gills that are decurrent - meaning they run right from the cap edge and down the stem. In this case, the stem is rudimentary, a short (often fluffy) number that's only a few centimetres long.
A handful of other oyster mushrooms exist, but are often much paler in colour. If they're much smaller, they're likely to be the oysterling family. A similar, all white version known as angel's wings is a great find as it's quite rare (and poisonous)!



Did you know?

These mushrooms are carnivores. In order to obtain the nitrogen they need, oyster mushrooms secrete a powerful toxin that stuns passing microscopic nematode worms, whereupon their sprawling fibres will seek out and enter their mouths and suck out their guts!

Fun fact from the Fungi Guy!