Amanita phalloides: The Death Cap

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by Michael Kuo

One of the deadliest mushrooms on the planet! I strongly urge you to learn to recognize this mushroom, along with the Destroying Angel, before picking any gilled mushrooms for the table. The toxins in Amanita phalloides are particularly sinister; see Mushroom Toxins for further information.

The Death Cap's defining features are: the sacklike white volva around its base; the white ring; the white gills; the white spore print; and the smooth (rather than lined) cap margin. Cap color is not the best thing to rely on in identification, since it is fairly variable. Older specimens have a distinctive, foul smell to them, but smell is never a very objective determiner.

There is a considerable amount of confusion over this species as it occurs in North America--and elsewhere. For many years, the old-school North American mushroom experts conflated Amanita brunnescens with Amanita phalloides; older mushroom books therefore document the Death Cap in places where it probably didn't occur. One widely held theory maintains that the true Death Cap is an import to North America, having arrived with European oak trees. More recent verified occurences of the Death Cap do tend to involve oak trees, especially European species--but the mushroom has also been verified under several species of pine, European or not. This type of debate over where the Death Cap is, and where it's supposed to be, isn't limited to North America, however; I once upset a Finnish mycologist's entire world-view by finding it 200 miles north of its officially designated Scandinavian range.

Description:

Ecology: Mycorrhizal with oaks, especially live oaks, but also under other trees; summer and fall (winter on the West Coast); range unclear (see the paragraph above). I have found it in Pennsylvania and California.

Cap: 4-14 cm, nearly oval, becoming convex, then broadly convex to flat in age; smooth; sticky when wet, shiny when dry; color ranging from greenish to olive to yellowish to brownish, sometimes even white; sometimes with one or a few patches of white veil material; the margin usually not lined.

Gills: Attached or free from the stem; white, sometimes with a slight greenish tint; close.

Stem: 5-18 cm long; 1-3 cm thick; more or less equal, or frequently tapering to apex and flaring to an enlarged base; smooth or finely hairy; white or with tints of the cap color; with a persistent skirtlike ring that typically remains but is often lost; without a rim; with a white volva encasing the base, frequently underground or broken up.

Flesh: White throughout.

Spore Print: White.

Microscopic Features: Spores 7-12 x 6-9 µ; smooth; broadly elliptical to round; amyloid.

REFERENCES: (Vaillant ex Fries, 1821) Link, 1833. (Saccardo, 1887; Kauffman, 1918; Smith, 1975; Smith, Smith & Weber, 1979; Thiers, 1982; Arora, 1986; Jenkins, 1986; Phillips, 1991/2005; Lincoff, 1992; Lindgren, 1998; Tulloss, 2005; Miller & Miller, 2006.)

A miniature version of Amanita phalloides is recorded by Michael Wood and Fred Stevens in California.

Further Online Information:

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Kuo, M. (2001, September). Amanita phalloides: The death cap. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/amanita_phalloides.html