Cap color

Chestnut

Chestnut is a deep, rich reddish-brown shade that resembles the skin of a ripe horse chestnut. In the mushroom world, a cap of this color is usually associated with the highest culinary quality. Most often this color belongs to the noble boletes.

3 species in the database.

Noble chestnut mushrooms

David Arora and M.Ya. Zerova describe several outstanding species for which chestnut is the main adornment:

1. Bay bolete (Imleria badia): One of the best-loved autumn mushrooms. Its cap is a perfect chestnut-brown or chocolate color. In dry weather it looks velvety and matte, and after rain it turns slightly sticky. Its key feature — the yellow-green sponge under the cap quickly turns blue when pressed.

2. Chestnut bolete (Gyroporus castaneus): A very rare and beautiful mushroom that even got its name from its color. Its cap and stem are an even chestnut color, but unlike the bay bolete, its flesh doesn't turn blue when cut, and the stem has hollow chambers (a chambered stem). It is listed in the Red Book.

3. Pine bolete (Boletus pinophilus): This kind of porcini has a much darker, chestnut-reddish or even wine-brown cap compared with the common porcini (which is more often light brown).

Dangerous lookalikes

A chestnut cap is a fairly safe marker, since most poisonous gilled mushrooms have lighter or greenish shades. However, Roger Phillips warns that chestnut boletes can be confused with the inedible bitter bolete (Tylopilus felleus). The bitter bolete has a similar brown-chestnut cap, but its tube layer turns pale pink with age, and its flesh is unbearably bitter.

Questions and answers

Why does the bay bolete's cap shine after rain?

The cuticle (skin) of the bay bolete contains specific polysaccharides that swell when wet and form a thin sticky film. This feature is typical of many boletes; it helps the cap protect itself from waterlogging and rapid rotting.

If I found a chestnut-colored mushroom with gills, is it edible?

Some edible mushrooms, such as the poplar knight (Tricholoma populinum) or certain brittlegills, can have a chestnut-brown cap. However, brown gilled mushrooms also include many dangerous webcaps and pinkgills, so gills (instead of a sponge) call for much more careful identification.

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