Use

Not eaten

In any major mycological field guide (Roger Phillips's or M.Ya. Zerova's, for example), most of the species described carry the label "Not eaten" (Inedible / None) in the use or culinary value column.

This is the largest category of fungi on the planet. They never make it into the kitchen: they aren't salted, pickled or used in medicine.

24 species in the database.

Why a mushroom stays in the forest

There are three main reasons a mushroom ends up with the "Not eaten" status:

The most obvious reason. This group includes every mushroom containing toxins that damage human organs, cause hallucinations or severe digestive upset.

- Examples: Death cap (deadly), Panther cap, Yellow stainer, fibrecaps (Inocybe).

These mushrooms contain no poison (you could feed their tissue to lab mice with no consequences at all), but a person physically can't swallow them.

- Toughness: Dozens of polypore species with the texture of wood or cork. There's no way to cook them.

- Bitterness: Bitter bolete (Tylopilus felleus) — its bitterness is so fierce that no amount of soaking or boiling will remove it.

- Smell: Some mushrooms (for example, a mature common stinkhorn or the sulphur knight) reek of rotting meat, gas or tar.

David Arora describes this group with a wonderful term, "LBM" (Little Brown Mushrooms). The forest holds thousands of species of mycenas, pinwheels (Marasmius), small webcaps and galerinas.

They:

- Have caps 1-2 centimeters across and stems as thin as a thread.

- Have no distinct taste or aroma at all.

There's simply no practical point in picking them for food, and the risk of accidentally cutting a deadly poisonous little galerina among them is huge. That's why their edibility is often even "unknown" to science, and their status automatically reads "Not eaten".

Questions and answers

If a field guide says slugs eat an "inedible" polypore, why can't a person eat it?

The digestive system of slugs and insects is adapted to break down tough chitin and even wood. What counts as soft food for a slug is, for a human stomach and teeth, like a piece of rubber or wood.

What should I do if I accidentally picked a mushroom that isn't eaten (but isn't poisonous)?

Nothing bad will happen. You can simply leave it in the forest. But if it's a bitter bolete (Tylopilus felleus), make sure it doesn't end up in your basket of edible mushrooms: even a single cooked bitter bolete will ruin a whole pot of good porcini with its bitterness.

Sources

1.Зерова М.Я. та ін. Визначник грибів України. 1979
2.Roger Phillips. Mushrooms (Roger Phillips)
3.David Arora. Mushrooms Demystified
4.Index Fungorum