How to tell The prince from Yellow stainer

Cap 5-15 cm across; in young mushrooms firmly hemispherical to squared-off (a characteristic feature — the "square" young cap), later becoming convex to flat. Color white to cream, sometimes grayish-brown in the center. The most characteristic sign — touching the cap or its margin leaves bright chrome-yellow spots, especially noticeable in young mushrooms. The surface is smooth, slightly sticky in wet weather.

The cap of the prince is large, from 10 to 20, occasionally up to 25 centimeters across. When young it is hemispherical, almost globe-shaped, and with age it opens out to convex and flat. The surface is covered with numerous small, flattened scales in brown, reddish-brown or ocher-brown, arranged in concentric rows on a paler cream background. The surface may turn yellow when touched. A scaly brown cap on a pale background is a recognizable feature of the species.

Gilled hymenophore — gills free, crowded. When young — pale pinkish-gray, becoming with age dark brown, chocolate-blackish. Spore print dark brown. The gill color is typical of Agaricus — it doesn't help tell the yellow stainer apart.

The underside has gills. The gills are free, not attached to the stem, very crowded and narrow. Their color changes with age: in young mushrooms they are pale gray or pale pink, then turn pink and gradually darken to chocolate brown and almost black. The spore print is dark brown. Gills that turn pink and then dark are the key feature that separates Agaricus from the deadly poisonous white-gilled amanitas.

Stem 5-12 cm tall, 1-2 cm thick, cylindrical, with a pronounced bulbous base (a difference from other Agaricus species, whose stems are more even). Color white. The most important diagnostic sign: when cut, the flesh at the base of the stem and in the bulb is bright chrome yellow, often almost neon, and the reaction is fast (10-30 seconds). On the upper part — a white membranous ring, distinct in young mushrooms.

The stem is massive and cylindrical, up to 15–20 centimeters tall, white, with a noticeably thickened base. Its defining feature is a large, hanging ring near the top; below the ring the stem is covered with small whitish scales that turn yellow with age and when touched. There is no volva at the base, an important difference from poisonous amanitas.

Flesh firm, white in the cap and upper stem, bright yellow at the base of the stem even when undamaged. When cut, THE BASE OF THE STEM TURNS BRIGHT CHROME YELLOW — the main diagnostic sign. The cap yellows too, but more weakly. The smell is distinct and unpleasant — ink, phenol, medicinal ointment, creosote.

The flesh is white or pale cream, firm, and slowly turns yellow or slightly brownish when cut. The taste is mild and pleasant, nutty and mushroomy. Its most distinctive trait is a lasting sweet aroma of bitter almond or marzipan that holds up through frying and drying.

Distinct and unpleasant, with notes of ink, phenol, medicinal ointment, creosote, printer's ink. It comes out when you rub the flesh between your fingers, especially at the base of the stem. This smell is the most reliable sign: no edible Agaricus smells like this.

The smell is strong and pleasant, of almond and marzipan, one of the best diagnostic features of the species. If, however, the mushroom has an unpleasant inky or carbolic smell, and the base of the stem turns bright yellow when cut, it is the poisonous yellow stainer (Agaricus xanthodermus), and you must not pick it.