The following description is based on Jenkins (1983).
The cap of Amanita media is up to 78 mm wide, plano-convex with a slight depression in the center,
shiny, smooth, silvery white, with a nonstriate margin. The volval remnants are present as a few, small, floccose patches. The flesh is
white and up to 7 mm thick over the stem.
The gills are adnexed, crowded, creamy white; the short gills are truncate to slightly attenuate.
The stem is up to 50 × 14 -15 mm, solid,
creamy-white, smooth, with random, white, easily removed, floccose patches of volva
on the upper bulb, sometimes in rather large, easily broken patches, and
sometimes forming a low rim on the base of the stem. The basal bulb is
egg-shaped, with narrow end down, with the top of the bulb somewhat flattened (subabrupt)
up to 30 × 25 mm. The ring is apical, white delicate, soon disappearing.
The spores measure (9.4) 10.2 - 12.5 × 4.7 - 5.5 µm and are elongate to cylindric and amyloid.
Clamps are absent at bases of basidia.
Amanita media was originally described from Alabama, USA, where it occurs among loblolly pine and mixed hardwoods.
Jenkins notes that A. media is hard to place—"intermediate between sections Lepidella and Validae"
as in the case of A. radiata Dav. T. Jenkins. The cylindric spores and delicate partial veil
suggested section Lepidella to Jenkins but the nonappendiculate
pileus margin and the form of the volva suggested section Validae
to him. A more extensive discussion of "borderline" taxa can
be found on the page for Amanita radiata (link above). As in that case, Amanita
media has a noncellular subhymenium which could argue for its placement in section Lepidella.
—R. E. Tulloss
In herb. David T. Jenkins, Univ. Alabama, Birmingham
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The field may contain magenta text presenting data from a type study
and/or revision of other original material cited in the protolog of the present taxon.
Macroscopic descriptions in magenta are a combination of data from the protolog and
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taxon (including non-type material and/or material not cited in the protolog).
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this text is appropriate.
Olive text indicates a specimen that has not been
thoroughly examined (for example, for microscopic details) and marks other places in the text
where data is missing or uncertain.
The following description is derived entirely from the protolog of the present species (Jenkins 1983).
from protolog: up to 78 mm in diam., plano-convex with slight depression in center, shiny, smooth, silvery white, with distinct tannish tint primarily on disc; context white, up to 7 mm thick at center, tapering toward margin; margin non-striate; universal veil few, small, floccose patches.
from protolog: crowded, adnexed, creamy-white; lamellulae truncate to slightly attenuate./font>
from protolog: up to 50 × 14 - 15 mm, creamy-white, smooth; partial veil apical, white, very delicate, soon disappearing; context solid; basal bulb obovate, up to 30 × 25 mm; universal veil remnants as random, floccose patches on upper bulb, white, easily removed.
from protolog: Odor not distinct. Taste not recorded.
from protolog: filamentous hyphae undifferentiated, moderately branched, no clamps, 2 - 7 µm diam; inflated cells abundant, mostly terminal, mostly elongate, up to 191 × 38 µm.
from protolog: bilateral; filamentous hyphae undifferentiated, no clamps, 2- 8 µm diam; inflated cells elongate, terminal.
from protolog: inflated ramose to subcellular, no clamps.
from protolog: up to 43 × 4 - 11 µm, mostly 4-sterigmate, but with a conspicuous number of 2-sterigmate, thin-walled; no clamps.
from protolog: filamentous hyphae at base of stipe abundant, sparsely to moderately branched, no clamps, 3 - 7 µm diam, some gelatinization, irregularly disposed; inflated cells abundant, globose, subglobose, broadly elliptic, up to 78 × 78 µm, very few small elliptical cells, mostly short, terminal chains; tissue on pileus the same.
from protolog: filamentous hyphae undifferentiated, sparsely branched, no clamps, 3 - 6 µm diam; inflated cells terminal, clavate, longitudinally oriented, up to 154 × 41 µm, most smaller.
from protolog: almost exclusively filamentous hyphae, moderately branched, no clamps, 2 - 8 µm diam, interwoven; inflated cells sparse, small, terminal.
Since this taxon is apparently very similar to
radiata, of which very pale specimens have
found, it seems that one should consider whether the
latter taxon's name might not be a taxonomic
synonym of A.
media. Both taxa were originally collected
in the same roadside rest area a year apart.
Unfortunately, Jenkins did not provide a detailed
justification of novelty in his protolog for
The present species is segregated from
A. radiata by (1) absence of the relatively
submembranous patches of volva on the pileus
(however, apparently few volval remnants were on
the pilei of the material seen by Jenkins), (2) fine
radiating brown lines present on the pileus surface,
and (3) a nonstriate pileus margin. This is
not a very distinctive differentiation of a species
within section Validae. Jenkins never
gave an indication of the size of the sample of
spores that he measured.
Of the few specimens that we have seen that fall into
the media/radiata grouping, so far all
share the same nrITS and nrLSU sequences.
Here is a sporograph comparing media and
radiata from that point of view:
New studies of the types and DNA sequencing of them
(if possible) would be very useful.
Comparison of the nrITS and nrLSU of
media/radiata material with sequences of
the same loci derived from material of Amanita
canescens also suggests a high degree of
similarity. In the latter case, recent research
has indicated that a single gene (nrLSU) consensus
tree of the cited taxa and others that are
morphologically and genetically similar in section
Validae includes media/radiata
and canescens in a well supported clade
having canescens as a well-supported
Here is an extension of the previous sporograph
that includes canescens:
The average length/width ratio (Q) of the spores for
A. canescens is distinctively smaller than the
value(s) for media/radiata—1.60
- 1.75 vs. 1.90 - 2.12.
—R. E. Tulloss
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