Oyster mushroom

The Oyster mushroom, or Pleurotus ostreatus, is a common mushroom prized for its edibility and lack of confusing look-alikes. Long cultivated in Asia, it is now cultivated around the world for food. It is related to the similarly cultivated "king oyster mushroom". Oyster mushrooms can also be used industrially for mycoremediation purposes.

Name
Both the Latin and common name refer to the shape of the fruiting body. The latin pleurotus (sideways) refers to the sideways-growth of the stem with respect to the cap while the latin ostreatus (and the English common name, oyster) refers to the shape of the cap which resembles the bi-valve of the same name. Many also believe that the name is fitting due to the flavor resemblance to oysters.

In Chinese, they are called píng gū (平菇). Meaning "flat mushroom".

Identification


The oyster is one of the more commonly sought wild mushrooms, though it can also be cultivated on straw and other media.

Cap
Size:5-25 cm broad, fan or oyster-shaped; Natural specimens range from white to gray or tan to dark-brown; margin inrolled when young, smooth and often somewhat lobed or wavy.

Flesh
Flesh white, firm, varies in thickness due stipe arrangement.

Gills and stem
Gills are white to cream, descend stalk if present. If so, stipe off-center with lateral attachment to wood.

Spores
The spores form a white to lilac-gray print on dark media.

Mycelium
The mycelium is white and grows rapidly.

Habitat
The Oyster Mushroom is wide-spread in temperate forests throughout the world. It is a saprophyte that acts as a primary decomposer on wood.

Edible uses
The oyster mushroom is frequently used in Japanese and Chinese cookery as a delicacy: it is frequently served either on its own, although sometimes stuffed: and in stir-fry recipes too with soy sauce.

Additional Information
Oyster mushrooms are a natural source of statin drugs. Studies have shown that they typically contain 0.4% to 2.7% statins on a dry weight basis. Z. Naturforsch Study. A number of studies on lab animals have shown that adding Pleurotus to the diet can reduce cholesterol under some conditions.

The oyster mushroom is also one of the few known carnivorous mushrooms. Its mycelia can kill and digest nematodes. This is believed to be a way to obtain nitrogen.

Oyster mushrooms contain a small amount of arabitol which can cause gastrointestinal distress in some people. Arabitol is a sugar alcohol similar to xylitol, manitol and sorbitol; these sugar alcohols are widely used food additives and can also have laxative effectives in susceptible individuals.