About Amanita
Collage of images of Amanita taxa.
Each image is linked to the taxon page providing a description of the
taxon depicted and a credit for the image.
The definition of the genus Amanita has been slightly complicated from a
morphological point of view by the inclusion of at least seven species in the
genus that are not
agaricoid (do not have the form of a typical gilled
mushroom with a central stem and have lost the ability to mechanically
discharge spores). Having already place all amanitas in our morphological
definition of the
Amanitaceae (see
About
Amanitaceae), our task of defining the genus
Amanita is made
easier.
The genus
Amanita includes all and only those members of the
Amanitaceae that produce a fruiting body (
basidiome) satisfying
exactly one of the following conditions:
-
It is hypogeous (it has lost the ability to mechanically discharge its
spores and grows under ground).
-
It is secotioid (it has lost the ability to mechanically discharge
its spores and grows above ground) or agaricoid and exhibits the mode of
basidiome development (ontogeny) that is called schizohymenial
(growing from a solid mass without cavities in which all the parts of the
mushroom develop in place and then have to be split apart in final stages of
development).
In most of the world this reduces the practical matter of identification of
agaricoid specimens of
Amanita to the tasks of finding in that specimen
the same evidence that has been very clearly required since the publication of
the thesis of Dr. Cornelis Bas in 1969. An agaricoid or secotioid
mushroom is an
Amanita if and only if you can demonstrate that the specimen
-
has longitudinally acrophysalidic stipe tissue
-
is not a species of Limacella.
If an unopened button of the species is available, and you find that all the
developing elements (cap, stem, gills, volva) of a mature mushroom are visible
as distinct, shadowy regions in a cross-section of the button and that these
developing elements are interconnected by tissue so that there is no open space
within the button, then
you have demonstrated that the probable ontogeny of the button is
schizohymenial—literally that the faces of adjacent gills must be
split apart from each other as the development of the mushroom continues.
If an agaric exhibits schizohymenial development
it can only be an
Amanita—this ontogeny is restricted entirely to the
genus
Amanita. Hence, you don’t have a
Limacella.
If the collector of your specimen found no buttons or found them but did not
retain them for your edification, then you should view the page
About Limacella on which distinctive
morphological features of
Limacella are described; and you must show
that the material you have in hand lacks those distinctive characters.
Here is a simple method of separating dried specimens of Limacella and Amanita with microscopic examination of the gill edge. Check whether the edge of a gill is fertile (has spore-bearing basidia growing from it) or sterile (doesn't have basidia growing from it).
In the Amanitaceae, the fertile condition occurs only in Limacella. The sterile condition is found only in Amanita.
The sterile condition can be recognized as follows: In Amanita, the gill edge is comprised of a “cable-like” grouping of hyphae running the length of the gill edge and giving rise to balloon-like cells of various shapes (singly or in short chains) which separate, collapse, gelatinize, and/or break, facilitating the the separation of the gill edge from the stem or from the partial veil (ring, annulus, skirt) as the elements of the expanding Amanita basidiome are separating.
The reader may think, "Surely, I recognize an
Amanita when I see one." In response it must be said that, in many cases (especially with regard to taxa similar to locally familiar taxa), the reader probably
does know his/her amanitas by sight. On the other hand, it still happens that professional mycologists name species in the genus
Amanita that are
not amanitas. Wouldn't you like to avoid that happening to you?
The type species of the genus is
A. muscaria (L.: Fr.) Lam. [ ≡
Agaricus muscarius L. (1753) ].
To start exploring
Amanita with an alphabetized directory of the taxa included on this site, go
here.
Subgenera
The genus is divided into two subgenera depending on the reaction of spores to an iodine solution (e.g., Melzer's Reagent). A darkening reaction of a spore's wall to this solution is called an
amyloid reaction and lack of such a reaction classifies a spore as
inamyloid.
Species having spores producing the amyloid reaction are classified in
Amanita subgenus
Lepidella. The type species of this subgenus is
A. vittadinii (Moretti) Vitt. The directory page for this subgenus can be found
here.
The species with inamyloid spores are placed in
Amanita subgenus
Amanita. The type species for subgenus
Amanita is the same species that is the type for genus as a whole—
A. muscaria. For an alphabetized directory of the taxa of subgenus
Amanita, go
here.
Sections
The subgenera are further divided into sections. There are seven sections currently recognized in
Amanita. In the pages of this site, sectional names follow the usage of Corner and Bas (1962) and Bas (1969) as emended in Yang (1997). A description of the sections of the genus can be found
here.
[NB: Images and well-documented dried collections of material from outside their respective regional collecting areas are sought by both editors of this site.]