East Asian brown death cap

A small-to-medium Amanita with a smoky, radially-streaked cap 4-9 cm, ranging from dark ashy grey to nearly black - the feature that names it.

Beneath are pure white free gills; the white stem carries a ring and rises from a firm, sac-like white volva.

The spore print is white.

The deadliest species in southern China's poisoning statistics - amatoxins that no cooking can destroy, in a plain dark mushroom easily taken for an edible.

In one 1994-2012 regional cohort it caused an estimated 41% of cases and 43% of deaths.

Amatoxins - cyclic octapeptides, chiefly α-amanitin - shut down RNA polymerase II, so cells stop making protein and the liver and kidneys fail.

They are not destroyed by cooking, drying, freezing or soaking.

Poisoning runs in four phases:

1. 1A symptom-free latency of 6-24 hours.
2. 2Then violent vomiting and watery diarrhoea.
3. 3Then a deceptive false recovery of one to three days, while liver enzymes quietly climb.
4. 4Then liver and kidney failure on days 3-5, often fatal without intensive care or a liver transplant.

The long silent start is what makes it so deadly - victims rarely connect their illness to the meal.

Never eat it. Amatoxins survive all cooking and preservation, and the delayed onset hides the danger until organ damage is underway.

Always uproot the whole stem to check for a volva, and treat every white-gilled, white-spored mushroom with a ring and a sac-like base as lethal.

Ectomycorrhizal with oak and Castanopsis, in the subtropical and warm-temperate broadleaf forests of eastern and southern China and Japan.

Often found in secondary woodland close to villages.

Fruits in summer and autumn, later than its spring-loving cousin Amanita exitialis.

It appears within days of warm, sustained rain.

An ectomycorrhizal Amanita: the mycelium lives for years threaded through tree roots.

A fruitbody is only the brief above-ground tip of that partnership, pushed up within a few days of warm rain.

Watch for confusion with:

• Edible grey- and brown-capped mushrooms gathered locally.
• The egg stage of the paddy straw mushroom (Volvariella), which has a pink spore print and no ring.
• Other deadly Amanitas of the region.