Laura Smith
Oyster mushrooms, or Pleurotus ostreatus, are edible fungi that resemble oysters in shape and texture. They are prized for their culinary and medicinal value, and are used in cuisines worldwide. Oyster mushrooms are widespread in many forests, particularly those that are temperate and subtropical. Oyster mushrooms are also known for their ability to decompose wood and remediate soil. While they are generally safe to consume, some people may experience mild allergic reactions. Additionally, there are several toxic mushrooms that resemble oyster mushrooms, such as the mock oyster mushroom, which has a distinctive orange hue and a unique smell. The peeling oysterling is another similar-looking species that is not toxic but is considered too small to be worth consuming. The hygrophanous nature of oyster mushrooms, particularly evident in the peeling oysterling variety, contributes to their distinctive appearance and makes them a fascinating subject for foragers and mycologists alike.
| Characteristics | Values |
|---|---|
| Cap | Broad, fan or oyster-shaped, 2–30 cm wide, white to grey or brown, smooth, margin becomes wavy |
| Flesh | White, firm, thickness varies due to stipe arrangement |
| Gills | Whitecoloured, sometimes becoming yellowish, and decurrent if a stalk is present |
| Stipe | Up to 4 cm long and thick, off-center and attaching laterally to wood |
| Spore print | White to lilac-grey |
| Aroma | Bittersweet aroma of benzaldehyde or bitter almonds |
| Habitat | Temperate and subtropical forests, widespread but absent from the Pacific Northwest of North America |
| Season | Fruits in the cooler time of the year |
| Taste | Mild with a slight odor similar to anise |
| Toxicity | Edible, but some people may experience a mild allergic reaction |
| Cap | Initially hemispherical, then broadly convex or almost flat, 1-7 cm in diameter, rufous brown in the center, fading to honey yellow towards the edge |
| Cap | Bland pale tan or off-white/gray, gelatinous and peels away |
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What You'll Learn
Oyster mushrooms are edible and used in cooking
Oyster mushrooms are often sold in grocery stores and farmer's markets, with the most common varieties being grey, golden (yellow), and king oyster mushrooms. Less common varieties include pink and blue oyster mushrooms, which can occasionally be found at farmer's markets. They can also be grown at home with the right equipment or a countertop kit.
When cooking oyster mushrooms, it is important to clean them gently with a damp paper towel, tea towel, or mushroom brush. Rinsing or submerging them in water can affect their texture, making them mushy. To cook, heat a non-stick pan to medium-high heat and add oil. Arrange the mushrooms in a single layer and cook without turning until one side is golden brown and crisp. They can be seasoned with salt and pepper and served with herbs such as parsley.
Oyster mushrooms are a good source of nutrition and can be used as a vegetarian alternative to meat in dishes such as stir-fries, soups, and stews. They can also be breaded or stuffed. In Japanese, Korean, and Chinese cuisine, they are considered a delicacy. Oyster mushrooms are also used in sauces, such as vegetarian oyster sauce, and industrially for mycoremediation purposes.
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Oyster mushroom caps are hygrophanous, changing colour when wet
Oyster mushrooms (Pleurotus ostreatus), also known as grey oyster mushrooms, oyster fungi, hiratake, or pearl oyster mushrooms, are characterised by their oyster-shaped caps. Oyster mushrooms are widespread in many temperate and subtropical forests worldwide, although they are notably absent from the Pacific Northwest of North America. They are saprotrophs, primarily decomposing wood from deciduous trees, particularly beech trees.
Oyster mushrooms are highly regarded in the culinary world and are commonly used in soups, stews, stir-fries, and sauces. They are also employed industrially for mycoremediation purposes, such as treating soil polluted with diesel oil. Oyster mushrooms are known to bioaccumulate lithium and exhibit predatory behaviour towards nematodes, which may be a mechanism for obtaining nitrogen.
While oyster mushrooms are generally safe for consumption, it is important to distinguish them from similar-looking toxic mushrooms, such as the mock oyster mushroom (Phyllotopsis nidulans), which has a distinctive orange hue and a unique odour. Other toxic mushrooms that resemble oyster mushrooms include Omphalotus nidiformis, found in Australia, and certain toxic Lentinellus species with hairy caps and jagged gill edges.
Notably, oyster mushroom caps are hygrophanous, meaning they exhibit colour changes when wet. The cap becomes more transparent as it absorbs water, while it appears opaque when dry. This characteristic can make determining the actual cap colour challenging, as it may vary with the weather. The colour of the peeling oysterling, a variety of oyster mushroom, is typically a bland pale tan, off-white, or gray.
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Oyster mushrooms are widespread in many forests
Oyster mushrooms, or Pleurotus ostreatus, are widespread in many forests. They are found in temperate and subtropical forests around the world, although they are notably absent from the Pacific Northwest of North America. Oyster mushrooms are saprotrophs, meaning they act as primary decomposers of wood, particularly deciduous trees, and beech trees. They benefit the forest ecosystem by decomposing dead wood and returning vital elements and minerals to the soil. Oyster mushrooms are often seen growing on dying hardwood trees, but they do not act parasitically. Instead, they grow on the increasing mass of dead and dying wood as the tree dies from other causes.
Oyster mushrooms are easily recognisable by their broad, fan or oyster-shaped caps, which can range from 2 to 30 centimetres (1 to 12 inches) wide. The caps are typically light brown and sometimes ashy, with a smooth surface that becomes wavy at the margins. Oyster mushrooms are pleurotoid, meaning they have kidney-shaped or semicircular caps with gills attached laterally and directly out of the wood, with or without a stem. Oyster mushrooms are related to other Pleurotus species, such as P. pulmonarius and P. populinus, which are also edible but have lighter-coloured caps.
Oyster mushrooms are highly sought-after as they are edible and widely used in cuisine. They are a delicacy in Japanese, Korean, and Chinese cuisine, often served on their own, in soups, stuffed, or in stir-fries. Oyster mushrooms are also used in sauces, such as vegetarian oyster sauce, and breaded to create vegetarian alternatives to meat dishes. In addition to their culinary uses, oyster mushrooms have industrial applications for mycoremediation purposes. They have been successfully used to treat soil polluted with diesel oil, converting 95% of the oil into non-toxic compounds.
Oyster mushrooms have a unique appearance that sets them apart from other mushrooms, but there are some similar species that can be confused with true oyster mushrooms. One such example is the mock oyster mushroom (Phyllotopsis nidulans), which has a distinctive orange hue and a unique skunky smell. Beginners often confuse this species with true oyster mushrooms due to their similar shape, but the colour and smell are key distinguishing factors. Another similar species is the peeling oysterling (Crepidotus mollis), also known as the soft slipper, jelly crep, or flabby crepidotus. This mushroom is a miniature replica of the prized oyster mushroom and is often mistaken by hopeful foragers. However, it is not toxic, but its small size makes it unappealing for foraging as it would cook up to almost nothing.
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Oyster mushrooms are used for mycoremediation
Oyster mushrooms (Pleurotus ostreatus) are edible fungi with a range of culinary uses across the world. They are also used industrially for mycoremediation, a process that uses mushrooms to clean up hazardous waste and restore balance to the ecosystem.
Mycoremediation is an experimental bioremediation technique that uses the natural ability of mushrooms to produce enzymes to break down foreign substances. Oyster mushrooms, for example, can break down and convert plastics into bio-available food. Researchers in Mexico City found that introducing used diapers to oyster mushroom mycelium resulted in an 85% reduction in mass over two months. Even with the plastic of the diapers left on, there was still a 70% reduction in mass. Oyster mushrooms can also be trained to digest cigarette butts, which are thrown away at a rate of 750,000 tonnes per year.
Oyster mushrooms have been used to treat soil polluted with diesel oil, converting 95% of the oil into non-toxic compounds. They can also grow upon and degrade oxo-biodegradable plastic bags and contribute to the degradation of renewable polyethylene.
In Sonoma County, California, oyster mushrooms were used to cleanse the foundations of buildings burned in wildfires. Volunteers placed straw-filled tubes inoculated with oyster mushrooms around parking lots, roads, and hillsides. The mushrooms were used to divert runoff from sensitive waterways and break down the surfaces they were growing on, converting them into nutrients.
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Oyster mushroom look-alikes include the mock oyster and peeling oysterling
Oyster mushrooms (Pleurotus ostreatus) are edible fungi found in temperate and subtropical forests worldwide. They are named for their oyster-like shape and slippery texture. Oyster mushrooms are fan- or kidney-shaped, ranging from white to grey or light brown in colour. They are widespread and grow on decaying wood, particularly deciduous trees such as elm and beech.
Oyster mushrooms have distinct gills that are usually the fastest way to identify them. Their gills are decurrent, meaning they run down the stem, and they separate easily when fanned. Oyster mushrooms also have a weak stalk, typically a short, thin stub growing off-centre from the side of a log.
While the peeling oysterling is not toxic, it is also not considered edible due to its small size and insubstantiality. It grows in oyster mushroom-like clusters on hardwood logs and the bark of living trees in well-shaded, damp woodlands.
Other oyster mushroom look-alikes include the Luminescent Panellus (Panellus stipticus), a small, pinkish oyster-like mushroom with a dusting of "flour" on its surface, and the Honey Mushroom (Armillaria mellea), which has yellow caps with scurfiness and non-decurrent gills. It is important to distinguish between oyster mushrooms and their look-alikes, as some similar-looking species may be toxic or lead to illness if consumed.
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Frequently asked questions
Yes, oyster mushrooms are hygrophanous, which means their colour changes as they take in or lose water.
Oyster mushrooms can range from white to grey or brown. The peeling oysterling variety is a bland pale tan or off-white/grey colour.
Oyster mushrooms have a broad, fan or oyster-shaped cap, which can be 2-30 centimetres wide. The gills are whitish, sometimes becoming yellowish, and the stipe, if present, is off-centre and attaches laterally to wood.
Oyster mushrooms are edible and used in various dishes across different cuisines. However, some people may experience a mild allergic reaction to them.
Mock oyster mushrooms are not edible and have a distinctive orange hue and a unique smell that sets them apart from true oyster mushrooms. They are also known as orange oysters due to their similarity in shape to oyster mushrooms.
