The following is largely based on the descriptions by Bresinsky and Besl
and Neville and Poumarat (2004).
The cap of Amanita virosa
is 29 - 123 mm wide, white, sometimes pale cream-colored, sometimes with
yellowish or pale orangish tan tints in the center with age, hemispheric when young, soon conico-campanulate,
with a broad umbo, smooth, viscid when moist, shiny when dry, not
symmetric (with an irregular shape, not circular, often lobed), with a nonstriate
and nonappendiculate margin.
The volva is usually absent but rarely occurs as a few white membranous
patches. The flesh is white,
thick in the center of the cap, thin towards the margin.
The gills are quite
close, pure white to cream, with a flocculose edge. The
short gills are truncate.
The stem is 50 - 165 × 7 - 15
(-20) mm, cylindrical, white, solid to pithy-hollow, scaly below the
ring (often illustrated with recurved pointed scales), arranged in
concentric rings and somewhat overlapping each other; in some cases the
scales are robust. The bulb is 16 - 48 mm wide. The ring is white to yellowish, skirt-like,
membranous, fragile, collapsing rapidly on the stem, and in the upper quarter of the stem. The volva is
membranous, white, sometimes taking on a pinkish tint at maturity,
arising from the upper surface of the bulb, limbate, and usually
collapsing against the stem base. The flesh is pure white and unchanging.
The odor is strongly of a old rose or honey, in age or drying. This species is deadly POISONOUS.
Bresinsky and Besl (1990) measured
spores as follows: 8.2 - 11.3 × 6.7 -
9.7 µm and are subglobose to broadly ellipsoid and amyloid. Clamps are absent at
bases of basidia. Neville and Poumarat (2004) measured spores as
follows: 8 - 11 × 7.5 - 10 µm and are globose to subglobose to broadly
ellipsoid and amyloid. RET measured spores from material collected
from France, Norway, and Switzerland as follows: (6.6-) 8.2 - 10.5
(-13.0) × (6.1-) 6.9 - 9.5 (-12.6) µm.
Amanita virosa is deadly poisonous.
This species turns a beautiful and bright
yellow on all surfaces when exposed to a 10% KOH solution.
Amanita virosa was originally
described from Sweden and is known from Europe and eastern Asia. Neville and Poumarat report this species under beech (Fagus sylvatica), chestnut (Castanea satiba), pine (Pinus), spruce (Picea abies), and fir (Abies alba).
[Ed. Note: Although the present species has been reported from eastern Asia and has been confirmed genetically there (e.g., in Jilin Province, China), the name has apparently been misapplied to a number of different species. For example, see below.—Zhu L. Yang and RET]
=Agaricus virosus Vitt. nom. inval. p.p. 1835. Descr. Fungh. Manger.: 135, pl. 17. [Posterior homonym. ICBN §53.1] [Misapplication in part—concept including both A. verna and A. virosa.]
non Agaricus virosus Sowerby. 1797-1805. Col. Fig. of English Fungi or Mushro. : pl. 407, 408. [ affin. Stropharia semiglobata (Batsch : Fr.) Quél.] [per Neville and Poumarat (2004: 591)]
For more extended synonymy see the Amanita Nomenclator (t.b.d.).
The editors of this site owe a great debt to Dr. Cornelis Bas
whose famous cigar box files of Amanita nomenclatural information
gathered over three or more decades were made available to RET for computerization
and make up the lion's share of the nomenclatural information presented on this site.
Each spore data set is intended to comprise a set of measurements from a single specimen made by a single observer;
and explanations prepared for this site talk about specimen-observer pairs associated with each data set.
Combining more data into a single data set is non-optimal because it obscures observer differences
(which may be valuable for instructional purposes, for example) and may obscure instances in which
a single collection inadvertently contains a mixture of taxa.