When identifying a mushroom that we collected in the field, we should define its predominating characteristics. At the time of collection we need to pay attention to certain factors that can be seen best when the sample has maximum freshness.
The external appearance of a mushroom, within the same species, can be highly variable depending on the age of the specimen we are examining. Often, when we compare our sample to the one on the picture of a mushroom guide, it can look very different, even if it is from the same species. Thus, it is best to collect various specimens of the mushroom at different stages of development, so that we can see the changes in the appearance of the species. In any case, we should always collect whole specimens, including the stalk, as certain features found at the base of it are lost in not doing so.
If you are going to study the sample immediately, try to save it under “fresh” conditions, ideally wrapped loosely in foil and at the bottom of the fridge, which will keep it well for a few days (depending on the species). It is not recommended to freeze fungi for further study, because as soon as they begin to thaw they lose the structure and consistency.
On the other hand, we must pay special attention to those features that can only be seen in the field, as once at home these features will be lost or forgotten, and are often very important. To avoid this, the data should be recorded at the time of sample collection. Here we go through the main ones that you should be looking for.
Each mushroom species is the result of an evolutionary process that has formed its own characteristics within a given environment, to which it is fully adapted. Thus, according to the environment that surrounds us, we know which species we can potentially find. In more detail, these features are:
- Type of vegetation found: prairie, pine, oak, etc..
- Soil type, especially if calcareous or siliceous
- Substrate on which the fungus grows: earth, wood, dung, etc. .
- If it is a trunk of a tree or a stump, what kind of tree it is.
- Time of occurrence: this factor is also known as phenology. Just note the date of sample collection, as each species has a characteristic timing
PS: this app can be handy if you want to note down the places where you found each type!
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At this point, consider the morphological characteristics of the sample. As an amateur, consider only the ones visible to the naked eye or with a magnifying glass. Professionals would consider also the microscopic characteristics.
Although the typical mushroom is umbrella-shaped, with a hat (or pileus) held by a stalk (or stipe), they can take many forms:
- Shape: flattened, funnel-shaped, convex, conical, hemispherical, etc
- Size: it can remarkably vary within the same species
- Color: can also be very variable within the same species.
- Cuticle: may be viscose, scaly, fibery, cracked...
- Margin: grooved, fringed, wavy, cracked, etc...
This is the fertile part of the mushroom where the spores are produced.
- Type: gills, tubes, needles, or reticulate.
- Junction with stalk: this is mainly used with gills. The gills may be:
- Short-gills: they do not extend from the stalk to the margin
- Marginate gills: when the transversal and the longitudinal parts have different colors
- Forking: single gills become double in some points
- Color: very often, the color of the hymenium varies with the maturation of the spores.
- Density: used for mushrooms with very dense or very spaced gills
- Shape: cylindrical, club-shaped, narrowed at the base, etc ...
- Size: varies according to the size of the mushroom, but it is important to look at its relative size to the cap.
- Ring: certain mushrooms in their juvenile stages have a membrane, called partial veil, covering the hymenium, extending from the edge of the cap to the stalk. When the mushroom becomes bigger, this membrane break, leaving behind a ring or skirt on the stalk.
- Volva: some mushrooms that are egg-like are covered by a membrane called the universal veil, which breaks when the mushroom grows, leaving behind a bag at the base of the stalk called volva.
- Other features of the stalk: it can have scabers, a hollow center etc…
Smell and flavor (without risks) play an important role in the identification of mushrooms.
Many mushrooms have they own particular smell, which is detectable mainly in fresh, newly collected samples. Often these scents are similar to recognizable smells, well defined as anise, bitter almonds, flour, lye, coconut, etc...
In theory, trying a small piece of a mushroom to appreciate its taste poses no risk, because the amount needed is minimal and it should always be spit after the taste has been identified. However, it is not recommended for non professionals. Possible flavors that define mushrooms are sweet, sour, spicy, etc..
Fungi, like all living things, have a complex chemical composition, which sometimes can be used in the determination of the species. There are two different types, depending on the source of the chemical reaction:
Oxidation (intrinsic reaction)
Some mushrooms contain substances that change color when in contact with air. This can be seen by cutting the sample. In other cases, the change in color is observed later, when the mushroom has been manipulated (for example when cooked).
Use of chemical reagents (extrinsic reaction)
Standard laboratory reagents are used to distinguish one species from another. They should not be used at amateur level.
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