''Amanita atkinsoniana'', also known as the Atkinson's amanita, is a species of

fungus A fungus ( : fungi or funguses) is any member of the 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, separately from th ...

in the family

Amanitaceae The Amanitaceae is a family of mushroom-forming fungi. ''Amanita'' Pers. is one of the most specious and best-known fungal genera. The family, also commonly called the amanita family, is in order Agaricales, the gilled mushrooms. The family co ...

. 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 Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions. These fo ...

. The

fruit body In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

is white to brownish, with

caps Caps are flat headgear. Caps or CAPS may also refer to: Science and technology Computing * CESG Assisted Products Service, provided by the U.K. Government Communications Headquarters * Composite Application Platform Suite, by Java Caps, a Java ...

that measure up to in diameter, and stems up to long and thick. The surface of the cap is covered with reddish-brown to grayish-brown conical warts. The

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

has a bulbous base covered with grayish-brown scales. The fruit bodies smell faintly like

bleaching powder Bleach is the generic name for any chemical product that is used industrially or domestically to remove color (whitening) from a fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers specifically, to ...

. Although not known to be

poisonous Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...

, the mushroom is not recommended for consumption.

Taxonomy

The species was first described by American botanist

William Chambers Coker William Chambers Coker (October 24, 1872 – June 26, 1953) was an American botany, botanist and mycology, mycologist. Biography He was born at Hartsville, South Carolina on October 24, 1872. He graduated from University of South Carolina, Sou ...

in 1917, in his

monograph A monograph is a specialist work of writing (in contrast to reference works) or exhibition on a single subject or an aspect of a subject, often by a single author or artist, and usually on a scholarly subject. In library cataloging, ''monograph ...

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 () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

in September and October 1914. The specific name honors George Atkinson, a

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to teach an ...

mycologist who collected and described mushrooms in the southern and eastern United States in the late 19th century. In 1952,

Marcel Locquin Marcel Locquin, born May 6, 1922, in Lyon, France, died March 18, 2009, was a French mycologist. Locquin rose to eminence in the field of mycology over several years of work with a number of Nobel Prize winners. He himself has won numerous awar ...

chose to place it in the genus ''

Armillaria ''Armillaria'' is a genus of fungi that includes the ''Armillaria mellea, A. mellea'' species known as honey fungi that live on trees and woody shrubs. It includes about 10 species formerly categorized summarily as ''A. mellea''. ''Armill ...

'' as ''Armillaria atkinsoniana'', but this change was not adopted by later authors. ''Amanita atkinsoniana'' is classified in the

stirps In ancient Rome, a gens ( or , ; plural: ''gentes'' ) was a family consisting of individuals who shared the same nomen and who claimed descent from a common ancestor. A branch of a gens was called a ''stirps'' (plural: ''stirpes''). The ''gen ...

''Microlepsis'' of subsection ''Solitariae'', in the

section Section, Sectioning or Sectioned may refer to: Arts, entertainment and media * Section (music), a complete, but not independent, musical idea * Section (typography), a subdivision, especially of a chapter, in books and documents ** Section sign ...

''Lepidella'' of the genus ''

Amanita The genus ''Amanita'' contains about 600 species of agarics, including some of the most toxic known mushrooms found worldwide, as well as some well-regarded edible species. This genus is responsible for approximately 95% of the fatalities result ...

''. Species in the subsection ''Solitariae'' are distinguished by several characteristics: a volva 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 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 A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e pressed against the surface.

Description

The

cap A cap is a flat headgear, usually with a visor. Caps have crowns that fit very close to the head. They made their first appearance as early as 3200 BC. Caps typically have a visor, or no brim at all. They are popular in casual and informal se ...

of ''A. atkinsoniana'' is 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 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 (''Amanita caesarea''), for example, which may resemble a small white sphe ...

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 In mycology, a partial veil (also called an inner veil, to differentiate it from the "outer", or universal veil) is a temporary structure of tissue found on the fruiting bodies of some basidiomycete fungi, typically agarics. Its role is to isola ...

remnants hanging along the edge. The

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

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

is long and wide, equal or tapering slightly toward apex, whitish, and

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