Agaricus abruptibulbus

The cap of Agaricus abruptibulbus reaches 5 to 12 centimeters across. When young it is bell-shaped or cylindrical, opening out with age to convex and flat. The surface is smooth, silky-fibrous, dry, pure white or cream; it slowly turns yellow when touched and with age, especially at the margin. Yellowing on touch is an important diagnostic feature.

The hymenophore is gilled. The gills are free, not attached to the stem, and very crowded. Their color changes with age: in young mushrooms they are pale pink or grayish-pink, later darkening to chocolate brown and almost black. The spore print is dark brown. The pinkish young gills are the key feature that distinguishes Agaricus from the white-gilled, deadly poisonous amanitas.

The stem is slender, white, 6 to 12 centimeters tall; its defining trait is an abruptly widened, rounded bulb at the base, as if cut off. In the upper part there is a large hanging ring — a trace of the veil. The stem may turn yellow when touched. There is no true sac-like volva at the base; do not mistake the distinct bulb of this Agaricus for an amanita's volva.

The flesh is white and thin, slowly turning yellow when cut, especially at the base of the stem. The taste is mild and pleasant, with no bitterness. Its main hallmark is a sweetish aroma of anise or bitter almond, which distinguishes this species from its unpleasant-smelling yellow-staining lookalike.

The smell is pleasant, sweetish, of anise and almond — one of the defining features of the species. But if the mushroom smells of ink or carbolic, and the base of the stem turns bright yellow when cut, it is the poisonous yellow stainer, and you must not pick it.