Have you ever found a mushroom in the wild or in your backyard and wondered if it is edible or poisonous? For mushroom foragers, knowing the difference between edible and poisonous mushrooms just by glancing at them is almost like the Holy Grail of foraging.
With about 14000 species, mushrooms are easily some of the most interesting fungi in the world. The interest in them is not limited to science though as many species are famous culinary delights. Quite a few of them (about 1%) are very poisonous. Plus, the variety in mushroom morphology is so wide from the common umbrella-shaped varieties to ball-shaped structures that look nothing like the mushrooms we are used to.
Though just a few mushrooms are poisonous, knowing how to differentiate between edible mushrooms from non-edible or poisonous mushrooms is far from a walk in the park. In this article, we’d discuss everything you need to know about the differences between edible and poisonous mushrooms, including why it’s such a tough call to make, some common poisonous mushrooms and their edible look-alikes, and much more.
Difference Between Edible And Poisonous Mushroom
Let’s start by stating from the get-go that some mushrooms are very deadly. Some are just poisonous without being deadly while others have toxins that would make you just a little sick when eaten. These mushrooms fall under the category of non-edible or poisonous mushrooms.
Also, there is no single or easy way to tell if a mushroom is edible or poisonous. For instance, you can’t just use the colors, shape, size, or features to identify a poisonous mushroom or an edible one.
Take the Amanita bisporigera for instance. Commonly called the destroying angel, it is a deadly mushroom capable of killing an adult when eaten. But in appearance, it looks similar to the Agaricus campestris, commonly called the meadow mushroom which is edible and is even used in some pizzas.
The Morchella esculenta, also known as the true morel (or just ‘morel’) provides another instance of the edible vs toxic mushroom conundrum. With its weird honeycomb, orange appearance, it’s easy to slap the ‘poisonous’ label on it. But it is actually edible and is considered one of the most delicious mushrooms in the world. But, you could easily confuse it with Gyromitra esculenta (commonly called ‘false morel’) because they look so similar at first glance. It is poisonous and would make you very sick if you eat one.
The edible oyster mushroom (Pleurotus ostreatus) and the non-edible Angel wing mushroom (Pleurocybella porrigens) are two common mushrooms that provide another great example of the difficulty in telling edible and poisonous mushrooms apart. In terms of physical characteristics alone, they have similar traits.
It doesn’t get any easier when you go a bit deeper beyond the physical appearance. For example, some poisonous mushrooms turn blue when you break or cut them. Here is the thing, mushrooms that change color and turn blue when cut include edible species.
So, when it comes to mushroom identification in terms of toxicity or lack of, it is done on a case-by-case basis. And it doesn’t get any easier simply because less than 3% percent of mushrooms are poisonous.
However, there are some general guidelines you can follow when determining if that tasty-looking yard mushroom or the one you saw growing in the nearby woods is edible or not. Check them out below.
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How to Differentiate Between Edible And Poisonous Mushroom
Before going further, it should be emphasized that knowing if a mushroom is edible or poisonous is almost impossible without accurately identifying it. The list below is simply a general guideline. Mushroom experts recommend that you should treat any mushroom as inedible in the absence of accurate identification.
Traditionally, edible or non-edible mushrooms are identified broadly using criteria like where they are found, the growth pattern, color changes when cut, season of growth, and physical traits.
Let’s take a deeper look into how to use these criteria when figuring out if a mushroom is edible or poisonous.
Physical traits
As already stated, a mushroom’s appearance is one of the first things to consider when trying to identify both types of mushrooms. Below are some tips to keep in mind:
Cap – Generally, the cap’s surface of non-edible mushrooms is rough. Edible mushrooms, on the other hand, have a smooth cap texture.
The shape of the cap also comes into play. Mushrooms’ caps are generally convex in shape. But while edible mushrooms retain that convex shape, the cap of poisonous mushrooms tends to flatten out with maturity.
The edible Chanterelle mushrooms break the mold though. They have trumpet-shaped caps with unmistakable wavy gills on the surface. Some are even convex-shaped.
Stem and volva – The part of the mushroom at the base of the stem is known as the volva. In poisonous species, the volva is usually thick and bulbous with a relatively fat stem above it.
Edible mushrooms, on the other hand, generally have smaller volvas and a slim stem that tapers outwards to become thicker near the cap.
The stem bears another indication of a poisonous mushroom. Unlike edible mushrooms, you’d find a ring-like protuberance around the stem of some poisonous mushroom species especially those in the Amanita mushroom family that includes the deadly destroying angel mushroom.
Gills – The gills are the rib-like structures found underneath the cap. Two gill-linked features are commonly used to differentiate between edible and toxic mushrooms.
In terms of color, edible mushrooms tend to have colored gills that change from pinkish to darker colors as the mushroom matures. Inedible mushrooms on the other hand come with white gills that never change color.
Secondly, the gills of poisonous mushrooms can extend from the cap right down the length of the stem or stalk. But in the edible species, the gills are restricted to the caps.
Color – The color, either on the cap, stem, or the whole mushroom can also aid in mushroom classification in terms of toxicity. The red color on the cap or stem or both usually indicates the mushroom is poisonous.
For instance, the red-capped Amanita muscaria, commonly called fly agaric, can be very deadly when consumed in large amounts. In small amounts though, it is strongly hallucinogenic.
So also is the all-yellow Omphalotus olearius, commonly called jack-o’-lantern. It is very poisonous and can easily be confused with some edible chanterelle mushrooms.
Growth environment and season
Where the mushrooms are found and the time of year they grow are also indicative of mushroom toxicity or edibility. Edible species are typically found in yards and open spaces with decomposing organic materials close to human habitats.
Poisonous mushrooms, on the other hand, are more likely to be found growing under trees like cedar, eucalyptus, conifers, and shrubs. Typical examples are the toxic mushrooms in the Amanita family sprouting under trees and woodlands in summer and fall.
Odor
The odor or smell emanating from mushrooms can also be used to tell if a mushroom is edible or poisonous. Yet again, like all the traits mentioned above, using the smell to determine mushroom toxicity isn’t set in stone.
To apply the ‘mushroom smell test’, simply crush the cap with your hands and inhale a bit. A nice, earthy, fruity, or zero smell indicates it is most likely edible. If the perceived smell is foul or unpleasant, on the other hand, the mushroom is likely poisonous.
Spores properties
The characteristics of the spores found in different mushrooms are usually used by mushroom experts to classify and identify them. This can also be used to peg a mushroom as either edible or poisonous.
Without being specific, mushrooms with white spores are likely to be poisonous. Edible mushrooms usually disperse black or dark-colored spores.
You can obtain the dispersed spore by placing a matured mushroom on a piece of paper for a few hours. For best results and contrast, use dark-colored and white papers; place a mushroom on each piece of paper.
Depending on the type of mushroom, you’d clearly see the color of the dispersed spores on either the dark-colored paper or white paper after a few hours.
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Steps for Accurately Identifying Edible or Poisonous Mushrooms
- Ask relevant questions like where it grows, the growth substrate, and what time of the year it is growing.
- Check the gills and note the color. You might also want to check for a ring on the stem, and the size of the volva after uprooting it.
- Cut the cap and see if it changes color or not. If it does, what is the color?
- You could also sniff the cut piece and note the smell coming off it.
- Check the spore print using the ‘paper test’ described above.
- Finally, take the results from the 5 steps above to an online catalog for mushrooms to help you identify the mushroom. There are several of these online resources including apps such as Book of Mushrooms and Shroomify.
You could also take advantage of social media mushroom groups on Facebook and the r/mycology subreddit on Reddit. Simply upload the pictures and the noticeable traits of the mushroom to get helpful identification advice from experts or veteran mushroom foragers in these groups.
Wrapping up
There is no single, accurate way to tell the difference between edible and poisonous mushrooms. This makes it critical that the default position to adopt on any unidentified mushroom is ‘poisonous and shouldn’t be eaten.’
That said, some parameters could be used to identify if a particular mushroom is toxic or edible. These include the physical features, smell, where the mushroom is found, and its growing season. But keep in mind that using these parameters can sometimes be misleading as so many edible and poisonous mushrooms share the same traits.
