Which will ultimately help you determine whether they are safe for consumption or not. Besides specific defining characteristics and distinct visual differences, another feature to consider is whether they bruise or bleed a specific colour. There are certain mushrooms that will change in colour once they are injured or damaged in any way. It is therefore important to observe if any colour changes occur when you cut into a mushroom – this can be incredibly helpful when trying to identify the specific type of mushroom as well as determining whether its poisonous or not.
Although an important and helpful feature, it is vital to note that colour change on its own is considered one of the least reliable ways to identify different mushroom types. The main reason being that there are always variations. Colour change can also vary significantly depending on the age of the fungus. Mushroom bruising and bleeding should thus be used as an additional tool and in combination with other mushroom identification measures.
Mushroom bruising involves nicking the top and bottom of the mushroom cap and observing any colour changes. As specimens that are not fresh don’t give reliable results, it is important to do this within the first 30 minutes of picking the mushroom.
Why exactly does mushroom bruising occur? When certain compounds present in the cell wall of the mushroom is exposed to air, a chemical reaction takes place that result in the colour change. Once you cut into the cap of the mushroom you are essentially breaking its cell wall, this in turn allows the oxygen in the air to interact with the compounds present in the mushroom and change them. Let’s use Gyroporus cyanescens as an example – When you nick its cap and break its cell wall, exposing it to the oxygen in the air, the variegatic acid present in the mushroom is converted to the blue-coloured molecule quinone methide.
There are many well-known blue bruising mushrooms. In fact, blue bruising is one of the most famous features of psilocybin-containing mushrooms (aka magic mushrooms). Blue bruising (along with two other features) is an indication that a particular mushroom can potentially be an active psilocybin mushroom. However, a common and very important rule for boletes is that you should under no circumstances consume a mushroom that has a red pore surface and bruises blue. As such a large amount of blue bruising boletes are poisonous, it is not only best, but vital, to avoid them entirely.
One of the biggest misconceptions is the fact that some people believe that all blue bruising mushrooms are safe to eat or are hallucinogenic. The bolete rule above proves that is simply not true. This potentially dangerous, or in many cases even life-threatening, myth/misconception further re-iterates why solely identifying mushrooms through bruising is not reliable and a bad idea overall.
When you cut into certain mushrooms they will exude a milky liquid substance. Although the term is Mushroom ‘bleeding’, it is not real blood in any way, but rather a natural latex that is generated when the mushroom is cut into or injured.
While the precise reasoning why these mushrooms produce the latex substance is not fully understood, it is believed to be a natural defence mechanism of the mushroom. This is mainly owed to its bitter taste and the fact that it instinctively dries to form a protective coating around the injury or cut to prevent bacteria or any other contaminants from entering.
Some of the most popular bleeding mushrooms are the mushrooms in the Lactarius genus. These mushrooms are commonly referred to as the ‘milky caps’ because of the milky latex they exude when injured.
A great example is the blue bruising and bleeding of Lactarius indigo, the indigo milk cap. When this mushroom is cut into it bleeds a bright blue latex that progressively turns green. A visual of this bright blue latex substance can be seen on the thumb of the individual in the image below.
Here are a few examples of bruising and bleeding mushrooms. Take note that this list is by no means exhaustive and that there are many more examples.
• Boletus campestris: This mushroom bruises blue or blue-green. Many yellow-pored boletes bruise blue.
• Russula rubescens: This mushroom bruise a reddish colour, which then slowly turns to black.
• Agaricus bisporus (white button mushroom): The Agaricus bisporus, commonly known as the white button mushroom, typically bruises a pinkish colour. You can stick your finger into a grocery store-bought white button mushroom to test it out.
• Mycena haematopu: This mushroom bleeds a purplish colour.
• Psilocybe cubensis: The stems of the Psilocybe cubensis bruise blue or blue-green. This is a hallucinogenic mushroom, but its important to note that not all hallucinogenic mushrooms bruise blue.
• Lactarius chrysorrheus: Bleeds a white latex substance that dries to a deeper yellow colour.
• Lactarius helvus (maple syrup milky cap): The Lactarius helvus, commonly known as the maple syrup milky cap, bleeds colorless latex that smells like maple syrup.
Next time you are identifying mushrooms, check for bruising and/or bleeding. Although no identification is guaranteed and mushroom bruising and/or bleeding it not considered a reliable identification tool on its own, it can provide you with some important and helpful information in your mushroom identification process.
If you are using mushroom bleeding in your mushroom identification process, it is essential to observe and take note of both the initial liquid colour as well as the final dried colour, as these two colours will often be different.