Amanita atkinsoniana
Encyclopedia
Amanita atkinsoniana is a species of fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

 in the Amanitaceae
Amanitaceae
Amanitaceae are a family of fungi or mushrooms. The family, also commonly called the Amanita family, is in order Agaricales, gilled mushrooms...

 family. It is found in the northeastern, southeastern, and southern United States as well as southern Canada, where it grows solitarily or in small groups on the ground in mixed woods. The fruit body
Basidiocarp
In fungi, a basidiocarp, basidiome or basidioma , is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not produce such structures...

 is white to brownish, with caps
Pileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...

 that measure up to 12.5 cm (4.9 in) in diameter, and stems
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...

 up to 20 cm (7.9 in) long and 2.5 cm (0.984251968503937 in) thick. The surface of the cap is covered with reddish-brown to grayish-brown conical warts. The stem
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...

 has a bulbous base covered with grayish-brown scales. The fruit bodies smell faintly like bleaching powder. Although not known to be poisonous, the mushroom is not recommended for consumption.

Taxonomy

The species was first described by American botanist William Chambers Coker
William Chambers Coker
William Chambers Coker was an American botanist-Biography:He was born at Hartsville, South Carolina on October 24, 1872. He graduated from South Carolina College in 1894 and took postgraduate courses at Johns Hopkins University and in Germany...

 in 1917, in his monograph
Monograph
A monograph is a work of writing upon a single subject, usually by a single author.It is often a scholarly essay or learned treatise, and may be released in the manner of a book or journal article. It is by definition a single document that forms a complete text in itself...

 of Amanitas of the eastern United States. Coker's description was based on several specimens he had collected from various locations in North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

 in September and October 1914. The specific name honors George Atkinson, a Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

 mycologist who collected and described mushrooms in the southern and eastern United States in the late 19th century. In 1952, Marcel Locquin
Marcel Locquin
Marcel Locquin, born May 6, 1922 in Lyon, France, died March 18, 2009, was a French mycologist....

 chose to place it in the genus Armillaria as Armillaria atkinsoniana, but this change was not adopted by later authors.

Amanita atkinsoniana is classified
Biological classification
Biological classification, or scientific classification in biology, is a method to group and categorize organisms by biological type, such as genus or species. Biological classification is part of scientific taxonomy....

 in the stirps Microlepsis of subsection Solitariae, in the section Lepidella of the genus Amanita
Amanita
The genus Amanita contains about 600 species of agarics including some of the most toxic known mushrooms found worldwide. This genus is responsible for approximately 95% of the fatalities resulting from mushroom poisoning, with the death cap accounting for about 50% on its own...

. Species in the subsection Solitariae are distinguished by several characteristics: a volva
Volva (mycology)
The volva is a mycological term to describe a cup-like structure at the base of a mushroom that is a remnant of the universal veil. This macrofeature is important in wild mushroom identification due to it being an easily observed, taxonomically significant feature which frequently signifies a...

 composed of cellular structures of varying shape; rows of large cylindrical to slender club-shaped cells that are never dominant; a stem that typically has a bulbous base and remnants of the volva
Volva (mycology)
The volva is a mycological term to describe a cup-like structure at the base of a mushroom that is a remnant of the universal veil. This macrofeature is important in wild mushroom identification due to it being an easily observed, taxonomically significant feature which frequently signifies a...

 on the surface that are concentrated towards the base; the volva is not membranous nor nearly membranous, never forming a limb at the base of the stem, and never forming patches on the surface of the cap, where the outer layer consists of hypha
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...

e pressed against the surface.

Description

The cap
Pileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...

 of A. atkinsoniana is 6 – wide, and depending on its age, ranges in shape from convex to flattened, sometimes with a shallow central depression. Its color can vary from whitish to yellowish-white, brownish-gray, brownish-orange to grayish-brown, and is lighter on the margin. The cap surface is covered with the remnants of the universal veil
Universal veil
In mycology, a universal veil is a temporary membranous tissue that fully envelops immature fruiting bodies of certain gilled mushrooms. The developing Caesar's mushroom , for example, which may resemble a small white sphere at this point, is protected by this structure...

 as small reddish-brown to grayish-brown, easily removable, conical warts. Approaching the edge of the cap, the warts gradually become small, woolly patches. The cap margin is smooth or has faint grooves mirroring the underlying gills, and has partial veil
Partial veil
thumb|150px|right|Developmental stages of [[Agaricus campestris]] showing the role and evolution of a partial veilPartial veil is a mycological term used to describe a temporary structure of tissue found on the fruiting bodies of some basidiomycete fungi, typically agarics...

 remnants hanging along the edge. The gills are free from attachment to the stem, close to crowded together, moderately broad, yellowish-white, and occasionally have a slight reddish stain. The lamellulae (short gills that do not extend completely from the cap margin to the stem) are truncate (cut off sharply) to attenuate. The stem
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...

 is 8 – long and 1 – wide, equal or tapering slightly toward apex, whitish, and floccose to smooth. The basal bulb is club-shaped, ventricose-fusiform or turnip-shaped, rounded or pointed, usually covered with rings of reddish-brown scales or warts of universal veil remains, often extending up the stem for a short distance. The universal veil on the stem base is quite unusual in Amanita, because it forms warts that extend nearly to the very bottom of the bulb. The stem often roots into the soil beneath the bulb with an elongated cord of mycelium
Mycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...

 known as a pseudorhiza. The partial veil forms an ring
Annulus (mycology)
An annulus is the ring like structure sometimes found on the stipe of some species of mushrooms. The annulus represents the remaining part of the partial veil, after it has ruptured to expose the gills or other spore-producing surface. An annulus may be thick and membranous, or it may be cobweb-like...

 that is somewhat membranous, fragile to moderately persistent, and yellowish-white to pale yellow. Eventually, as the mushroom matures, it collapses on the stem as a thin membrane. The flesh
Trama (mycology)
In mycology trama is a term for the inner, fleshy portion of a mushroom's basidiocarp, or fruit body. It is distinct from the outer layer of tissue, known as the pileipellis or cuticle, and from the spore-bearing tissue layer known as the hymenium....

 is white, with a weak odor of bleaching powder.

Microscopic characteristics

The spore print
Spore print
thumb|300px|right|Making a spore print of the mushroom Volvariella volvacea shown in composite: mushroom cap laid on white and dark paper; cap removed after 24 hours showing pinkish-tan spore print...

 is white. The spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

s are ellipsoid to elongated, hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...

 (translucent), thin-walled, and have dimensions of 9–12.5 by 5.5–8 µm
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...

. They are amyloid
Amyloid
Amyloids are insoluble fibrous protein aggregates sharing specific structural traits. Abnormal accumulation of amyloid in organs may lead to amyloidosis, and may play a role in various neurodegenerative diseases.-Definition:...

, meaning they will absorb iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....

 when stained with Melzer's reagent
Melzer's Reagent
Melzer's reagent is a chemical reagent used by mycologists to assist with the identification of fungi.-Composition:...

. The basidia (spore-bearing cells) are 35–60 by 7–13.5 µm, club-shaped, four-spored, with clamps at their bases. The cheilocystidia (cystidia found on the edge of the gill) are 15–45 by 10–30 µm, ellipsoid to club-shaped, and abundant. The cap cuticle
Pileipellis
thumb|300px||right|The cuticle of some mushrooms, such as [[Russula mustelina]] shown here, can be peeled from the cap, and may be useful as an identification feature....

 is up to 165 µm thick, and is made of interwoven to radial hypha
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...

e, 2.5–8 µm diameter, which is slightly to strongly gelatinized. The universal veil on the cap consists of mainly roughly spherical to ellipsoid but also club-shaped and elongated cells, up to 75 by 40 µm, arranged in short, terminal chains and relatively sparse hyphae, measuring 3–7.5 µm in diameter. At the base of the stem the universal veil tissue is very similar to that on the cap. Clamp connection
Clamp connection
A clamp connection is a structure formed by growing hyphal cells of certain fungi. It is created to ensure each septum, or segment of hypha separated by crossed walls, receives a set of differing nuclei, which are obtained through mating of hyphae of differing sexual types...

s are present in the hyphae.

Edibility

Pomerleau (1980) considers the mushroom as "doubtfully edible", while Orson
Orson K. Miller, Jr.
Orson Knapp Miller, Jr., born December 19, 1930, died June 9, 2006, is an American mycologist. He has published numerous papers in mycology and is responsible for the naming of many taxa, as well as being one of the authors erecting the genus Chroogomphus:...

 and Hope Miller, in their field guide
Field guide
A field guide is a book designed to help the reader identify wildlife or other objects of natural occurrence . It is generally designed to be brought into the 'field' or local area where such objects exist to help distinguish between similar objects...

 to North American mushrooms, list it as "possibly poisonous" (although they also indicate that no specific reports of toxins have been reported from the species), and recommend that in general, no species in Amanita subgenus Lepidella should be consumed.

Similar species

Because of the colored volva, A. atkinsoniana resembles A. onusta
Amanita onusta
Amanita onusta, commonly known as the loaded Lepidella or the gunpowder Lepidella, is a species of fungus in the Amanitaceae family of mushrooms. It is characterized by its small to medium-sized fruit bodies that have white to pale gray caps crowded with roughly conical, pyramidal, or irregular...

, which differs from A. atkinsoniana by the small to medium-sized fruit bodies with a grayish veil as dark gray to brownish gray warts and a basal bulb which is usually somewhat rooting. Sometimes the fruit bodies of A. atkinsoniana are confused with A. microlepsis which can be distinguished by the presence of reddish-brown to grayish-brown volval remnants and the rooting bulb of A. atkinsoniana.

Distribution and habitat

The fruit bodies of Amanita atkinsoniana grow on the ground in mixed coniferous and deciduous forests. They have been collected in Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...

, Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...

, Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...

, Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

, Michigan
Michigan
Michigan is a U.S. state located in the Great Lakes Region of the United States of America. The name Michigan is the French form of the Ojibwa word mishigamaa, meaning "large water" or "large lake"....

, North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

, New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...

, New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

, Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

, Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...

, Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

, Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

, Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...

, and West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

. One field guide
Field guide
A field guide is a book designed to help the reader identify wildlife or other objects of natural occurrence . It is generally designed to be brought into the 'field' or local area where such objects exist to help distinguish between similar objects...

 notes a preference for association with oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...

 where there is ground cover of blueberry (Vaccinium
Vaccinium
Vaccinium is a genus of shrubs or dwarf shrubs in the plant Family Ericaceae. The fruit of many species are eaten by humans and some are of commercial importance, including the cranberry, blueberry, bilberry or whortleberry, lingonberry or cowberry, and huckleberry...

) bushes. The mushroom has also been collected in Quebec, Canada. The southern extent of its range extends to the Mexican state of Michoacan
Michoacán
Michoacán officially Estado Libre y Soberano de Michoacán de Ocampo is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 113 municipalities and its capital city is Morelia...

. The mushroom fruits most commonly during late summer and fall after heavy rains.
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