Cap surface

Scaly

A scaly (squamulose) cap surface is one of the most striking and useful features for identification. When a cap is covered in scales, it looks like a tiled roof, reptile skin or tree bark.

Interestingly, the scales on mushrooms can have two completely different origins, a point both M.Ya. Zerova and David Arora are careful to stress.

24 species in the database.

Type 1: The mushroom's own torn skin

Here the scales are an organic, inseparable part of the mushroom itself. As it grows, the stem and cap flesh expand faster than the outer skin. As a result, the skin "can't take" the strain and tears apart, forming scales against the paler background of the flesh.

- Parasol mushroom (Macrolepiota procera): The textbook example. Its large, brown, angular scales can't be washed off by rain, because they are part of the cap.

- Honey fungus (Armillaria mellea): Has small, dark, hairy scales all over its honey-brown cap.

- Shaggy scalycap (Pholiota squarrosa): A mushroom that grows on trees and is covered entirely, from cap to stem, in sharp, stiff scales that stick upward.

Type 2: Remnants of the universal veil (warts)

Here the mushroom is born inside an "egg" (the membrane of the universal veil). As the mushroom grows, the membrane tears, and its upper part stays on the cap as white or gray spots. They sit on top of the mushroom's smooth skin.

- Fly agaric (Amanita muscaria): Its famous white spots are not torn skin, just debris stuck on from the protective cocoon. These scales (warts) are crumbly like cottage cheese and come off easily with a fingernail or get washed away by a downpour.

- Panther cap (Amanita pantherina): Has a deadly dangerous brown cap with dense white warts.

Questions and answers

If I find honey fungus without scales, is it a poisonous look-alike?

On genuine honey fungus the scales are very delicate. If the mushroom is old, or there has been heavy rain, the scales can wash off completely. However, the poisonous brick tuft (Hypholoma lateritium) and the dangerous sulphur tuft NEVER have scales at all — their caps are perfectly smooth from the start. So the presence of scales is a sign of edible honey fungus, and their absence (especially on young mushrooms) is a warning sign.

Can you eat scaly mushrooms, or do you need to peel off the skin?

With the parasol mushroom or honey fungus there's no need to peel off the scaly skin — they cook beautifully and taste great. The shaggy scalycap is usually cooked with its scales left on, but the mushroom is considered tough and low-quality (conditionally edible) and needs long boiling.

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