Death Cap Puffball Mushroom: How to Tell Them Apart

Every death cap starts as an egg. Wikipedia describes young specimens emerging from the ground as a white egg covered by a universal veil, which later breaks and leaves the cup-like volva at the base. At that stage it has no visible cap, gills or stem, just like a small puffball, and Wikipedia notes that immature death caps can be mistaken for puffballs, which is why some experts advise against collecting any Amanita at all. The Missouri Department of Conservation gives the same warning for the destroying angel, whose early stages could be mistaken for a puffball.

The Missouri Department of Conservation's instruction is to cut every puffball open from top to bottom and confirm it is smooth and plain throughout, with no sign of a developing cap or stem.

• Cut through the centre, from the top down through the base, so any hidden mushroom outline is split in half rather than missed.
• Puffball: a clean, uniform white interior with no gills and no internal structure (Missouri Department of Conservation; Practical Self Reliance).
• Amanita egg: the silhouette of a mushroom inside, with a cap, a stem and the beginnings of gills (Practical Self Reliance; Wikipedia on Lycoperdon perlatum). Treat this as a possible death cap or destroying angel.
• Earthball (Scleroderma): hard, with a dark interior, often half-buried with thick root-like strands at the base (Practical Self Reliance).
• Stinkhorn egg: layered tissue and a thick jelly-like layer inside (Practical Self Reliance).
• Any yellowing, olive or brown inside: a puffball that is turning to spores (Creative Sustenance; Wikipedia on Lycoperdon perlatum).

The cut test tells you when something is not a puffball. It does not make any wild mushroom safe to eat.

• A cottony skin that peels off easily is typical of the outer veil on an Amanita egg (Practical Self Reliance).
• A cup or sac at the base, often below soil level, is the volva left by the veil (Wikipedia). Dig the whole thing out to see it.
• Short spines or 'jewels' that rub off, leaving a net pattern, and a small hole at the top when mature, mark the common puffball, Lycoperdon perlatum (Wikipedia).
• A smooth white ball 8 to 20 inches across in a pasture or lawn fits the giant puffball (Missouri Department of Conservation).
• A thick, tough, warty skin points to an earthball (Practical Self Reliance).

None of these replaces the cut.

Extremely. Wikipedia estimates that 30 grams, about half a cap, can kill a human; symptoms usually start 6 to 12 hours after eating; the mortality rate is believed to be around 10 to 30%; and cooking, freezing or drying does not reduce the toxicity. The toxins are amatoxins, which destroy liver cells; see amatoxin poisoning for the stages and treatment. A small egg-stage death cap still contains them. If anyone has eaten any part of a white ball or egg from the ground, call Poison Control at 1-800-222-1222 (U.S.) now.

True puffballs are not where amatoxin poisonings come from. The dangers around them are three:

• Look-alikes. Amanita eggs contain amatoxins, and earthballs (Scleroderma) are toxic; both can pass for puffballs from the outside.
• Mature spores. Wikipedia describes lycoperdonosis, a rare lung disease caused by inhaling large amounts of spores from mature puffballs, including cases in teenagers and in dogs that played or dug near puffballs. More on white ball mushroom in yard.
• Old specimens. A puffball whose inside has gone yellow, olive or brown is turning into spore powder.

This site does not tell anyone that a wild puffball is safe to eat; that call belongs to an expert looking at the actual specimen.

The poisonings documented in these sources come from eating death caps. Wikipedia notes that authorities advise against handling suspected death caps or putting them in the same basket as mushrooms meant for the table. Use gloves or a bag over your hand to remove one, bin it rather than composting it, wash your hands afterwards, and keep it away from children and dogs.