How to tell Agaricus abruptibulbus from Death cap

The death cap's cap is 5–15 cm across. In young mushrooms it is hemispherical, later becoming flat and spread out.

The color varies from olive green and yellowish green to grayish and almost white — which is what makes identification tricky. The surface is smooth, slightly slimy in wet weather, with a characteristic radial pattern of darker fibers spreading from the center. The cap margin is even, without striations.

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 lamellate. The gills are crowded, thin and free — not attached to the stem. In both young and mature mushrooms they stay pure white — this is a critical diagnostic feature.

Not a hint of pink, cream or ochre, as in true Agaricus mushrooms. The gap between the gills and the stem is clearly defined. The veil is white and membranous, completely covering the hymenophore in young specimens.

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, 7–15 cm tall and 1–2 cm thick. Cylindrical, widening at the base into a characteristic club-shaped bulb wrapped in a membranous sack-like volva — the main diagnostic feature.

The color is whitish green, often with a snakeskin pattern of faint bands. In the upper third there's a well-developed, hanging white ring with remnants of the veil. The surface below the ring is faintly scaly.

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 doesn't change color when cut — and that's the treacherous part: none of the safety signs foragers are used to relying on work here. The flesh is thin and brittle in the cap, fleshy at the base of the stem.

It doesn't change color on contact with air, neither after a minute nor after an hour. No "lovely white flesh" should reassure you — it's precisely in the white flesh of the death cap that the concentration of amanitins is highest.

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 of a fresh mushroom is faint and hard to notice; in young specimens it's almost absent. Mature ones develop a slight sickly-sweet note, like wilted honey or stale dough.

This aroma isn't distinct enough to warn an inexperienced forager. Like other poisonous amanitas (the fly agaric, the panther cap), the death cap has only a faint, indistinct smell that gives no warning — yet another treacherous trait. A stronger odor appears only in rotting specimens.

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.