Mushroom Identification Basics

Identifying mushrooms requires a cautious approach, particularly if you intend to consume them. Since the majority of mushrooms are inedible and some of the most common varieties are poisonous, misidentification can lead to serious consequences. While photographs can offer assistance, they should not be solely relied upon for identification. Mushrooms can display significant variations in appearance due to differences in growth stages, environmental factors, and even damage from animals. Even if you are familiar with a certain mushroom species, these factors can cause it to resemble other species closely. To ensure accuracy, it is essential to consult multiple sources such as field guides, online resources, and experienced mushroom enthusiasts. Never rely on a single source, and always approach identification with a healthy dose of skepticism.

In order to have the best possible starting point for identification, pick the mushroom or, more precisely, the mushroom fruiting body from the ground, being careful to get the entire fruiting body in one piece. Mushrooms are fragile, which is why you can make picking easier by using a mushroom knife or a regular knife to pry the base of the mushroom from the ground or tree. The base of the stem may contain valuable identifying characteristics that would be missed if the stem were cut. If you're not planning to try to identify the mushroom in the field, put it in a well-ventilated basket, perhaps in a corner lined with moss, and take it home intact to identify it with literature.

Determining main group

After collecting the mushroom, the identification process begins by determining which group it belongs to. First, inspect the underside of the cap. If it is covered in gills, which are narrow strips arranged radially around the stem, the mushroom belongs to the gilled mushroom group, which includes russulas, amanitas, and many others. The familiar chanterelle and funnel chanterelle have structures on their underside that resemble gills, but they are actually ridges folded in a gill-like manner.

If there are small holes on the underside, the mushroom is a "pored mushroom". If the mushroom is soft and the pore layer can be easily detached, it is a bolete. A hard, woody, or tough find, often without a stem but sometimes with one, is a polypore. If the underside is full of spines, it is a hedgehog mushroom.

Occasionally, you may encounter round, stalked or stalkless "balls" without a clear cap. These are puffball mushrooms. Their spores are produced inside the fruiting body, which ruptures as it ages, and the spores are then spread by the wind.

These are some main groups of mushrooms, and after you have determined to which group the mushroom belongs to, you should continue by checking the characteristics to the mushrooms in the literature you are using.

Characteristics

Here are the characteristics typically mentioned in identification guides, mushroom books, and Mushroom World.

Caps

The shape can vary from bell-shaped to conical and flat to funnel-shaped. It is good to remember that the cap shape of a young mushroom is almost always domed and bell-shaped. It is useful to compare the shapes similar to the descriptions in the mushroom book to fully grown fruiting bodies.

The colour also changes according to the age of the fungus and the weather it is in. For example, the colours of the mushrooms in the Russula genus fade in the rain. Some mushroom caps clearly change with moisture, meaning they are hygrophanous. This usually means that the cap is significantly darker or a deeper color when wet and fades when dry. This fading is not due to loss of pigmentation, but rather due to the drying out of the spaces between the cells in the cap. Kuehneromyces mutabilis is a particularly good example of a hygrophanous mushroom; it is a dark honey colour when wet and the center of the cap begins to fade as it dries.

The hat skin also holds a lot of information: it can be slimy, sticky, dry, smooth, grainy, scaly, or speckled with fallen scales. Each property is helpful in the identification process.

Gills and Pores/Tubes

The gills and tubes vary depending on the species. Important characteristics are the width, thickness, and density of the discs, any branches present, and the way in which they are attached to the stem. The colour of the gills and tubes is also an important feature.

How a mushroom's gills are attached to the stem is important when identifying mushrooms. The following is a list of the standard types of gill attachments.

Free

Free gills are not attached to the stem, but rather are completely detached from it.

Adnate

Gills that are broadly attached to the stem are called adnate.

Decurrent

Gills that extend down the stem; it is called decurrent. The edge of a decurrent gill is usually not horizontal but approaches the stem at a slant, so the gill constantly gets wider as it approaches the stem.

Adnexed

Adnexed gills are attached to the stem at an angle, usually between 45 and 90 degrees. This means that the gills appear to be almost free from the stem, but are still attached.

Emarginate

Emarginate gills have roughly the same height for most of their length, then suddenly become much shallower just before reaching the stem.

Sinuate

Sinuate gills are just like emarginate gills, except they curve back down the stem bit just before attaching.

Spore Powder

The colour of the spore powder is a fairly consistent characteristic and therefore helps to distinguish between fungi. Identify the colour by taking a trace sample: place a healthy cap, with the discs facing down, on a single-coloured sheet of paper for a few hours. Examine the streaks of trace powder that appear on the paper. The spore powder can be for example white, light pink, brown, black, or yellow.

Foot

When identifying a mushroom, the characteristics of the stem should not be forgotten. The stem can be either hollow or solid, tough or fragile, slimy, sticky or dry, long or short, and everything in between. Pay attention to the shape of the stem, special features of its surface, the possible presence of a ring or web, and the characteristics of the base of the stem.

The shape of the stem varies from species to species, ranging from slender (some Russula mushrooms) to barrel-like thick (Boletus edulis). Perhaps on average, the stem of a mushroom is cylindrical or even, in which case the shape is not particularly significant when identifying the mushroom.

The upper part of the stem is mostly covered by the gills, which is why there may be a remnant of a veil such as a ring or annulus. Mushroom species with a ring on the stem include the Agaricus mushrooms, some Amanita mushrooms and Armillaria mellea, just to name a few examples.

The appearance of the annulus is also important. In some species, it opens upwards like a collar, but more commonly it hangs downwards. In the fly agaric, the lower edge of the annulus looks like a pleated skirt. In some species the annulus is double. In the case of Macrolepiota procera (parasol mushroom), the annulus seems to be detached from the stem and can be moved up and down while remaining intact.

Flesh

Mushroom flesh consists of threads and is often fibrous. In mushrooms in the genera Russula and Lactarius, the meat is brittle and breaks easily in all directions. An important characteristic to note when identifying is the colour of the mushroom flesh and whether the colour changes as the surface is cut. For example, the milky liquid that drips from mushrooms is a good indicator of a mushroom of the Lactarius genus.

Characteristic Scent

Some species have a typical scent, so it is important to become familiar with smelling the mushrooms. Elements of their surroundings, for instance, moisture or cold, can weaken the fungus's aroma. When describing the scent, it is common to resort to well-known aromas as points of comparison: common scents include licorice, onion, herring, flour, anise, or pencil. For example, the scent of the Lepista nuda (Wood Blewit) is often described as burnt rubber.

Habitat

When identifying fungi, it is also possible to acquire information from the tree species at the plant site. For example, Birch, aspen, pine, oak, and spruce have their own species in the Leccinum genus.

Last but not least

If all this sounds complicated, you can ask for help with your identifications on mushroom identification groups on Facebook, like the public Mushroom Identification group. There are also AI-powered apps for mushroom identification, but they often make mistakes.

It's also important to know that many mushrooms take years of experience to identify reliably.