''Russula crustosa'', commonly known as the crusty russula, is a species of

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

in the family

Russulaceae The Russulaceae are a diverse family (biology), family of fungi in the order Russulales, with roughly 1,900 known species and a worldwide distribution. They comprise the Russula, brittlegills and the milk-caps, well-known mushroom-forming fungi ...

. It is found in Asia and North America.

Taxonomy

The species was first described scientifically by American mycologist

Charles Horton Peck Charles Horton Peck (March 30, 1833 – July 11, 1917) was an American mycologist of the 19th and early 20th centuries. He was the New York State Botanist from 1867 to 1915, a period in which he described over 2,700 species of North American fu ...

in 1886, who made the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

collections in

Day, New York Day is a town in Saratoga County, New York, United States. The town is in the northwestern part of the county and is northeast of Amsterdam. Its population in the 2020 Census was 819. Day is located inside the Adirondack Park. History The to ...

. It is

classified Classified may refer to: General *Classified information, material that a government body deems to be sensitive *Classified advertising or "classifieds" Music *Classified (rapper) (born 1977), Canadian rapper * The Classified, a 1980s American ro ...

in the subsection ''Virescentinae'' of the genus ''Russula''. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''crustosa'' means "with a rind".

Common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

s for the species include "crusty Russula", "green quilt Russula", and "encrusted Russula".

Description

The

fruit bodies The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cyc ...

have

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 are initially convex before flattening out in age, often developing a central depression, and measure in diameter. In maturity, the dry cap surface breaks up into greenish patches around the margin. The margin of the cap has radial grooves that match 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 ...

on the underside. The closely spaced gills are white, cream, or pale yellow in color, and have an

adnate Adnate may refer to: * Adnation, in botany, the fusion of two or more whorls of a flower * Adnate, in mycology, a classification of lamellae (gills) * Conjoined twins Conjoined twins, popularly referred to as Siamese twins, are twins joined '' ...

attachment to the stem. Measuring long by thick, the stem is white to pale yellow, and becomes hollow in age. The

flesh Flesh is any aggregation of soft tissues of an organism. Various multicellular organisms have soft tissues that may be called "flesh". In mammals, including humans, ''flesh'' encompasses muscles, fats and other loose connective tissues, ...

is hard and compact (when young), and whitish. The

spore print 300px, Making a spore print of the mushroom ''Volvariella volvacea'' shown in composite: (photo lower half) mushroom cap laid on white and dark paper; (photo upper half) cap removed after 24 hours showing warm orange ("tussock") color spore print. ...

is pale

buff Buff or BUFF may refer to: People * Buff (surname), a list of people * Buff (nickname), a list of people * Johnny Buff, ring name of American world champion boxer John Lisky (1888–1955) * Buff Bagwell, a ring name of American professional wr ...

, and the

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s are elliptic in shape, and somewhat warted with a few fine interconnecting lines. They are

hyaline A hyaline substance is one with a glassy appearance. The word is derived from , and . Histopathology Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...

(translucent),

amyloid Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure (known as cross-β) and ability to be stained by particular dyes, such as Congo red. In the human ...

, and measure 6–9 by 5.5–7

μm The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...

. An

edible mushroom Edible mushrooms are the fleshy fruit bodies of numerous species of macrofungi (fungi that bear fruiting structures large enough to be seen with the naked eye). Edibility may be defined by criteria including the absence of poisonous effect ...

, ''R. crustosa'' has no distinguishing odor, and a taste ranging from mild to slightly acrid. Other greenish Russulas, including '' R. subgraminicolor'', '' R. aeruginea'', and '' R. variata'', can be most readily distinguished by their non-cracking cap surfaces.

Similar species

''Russula crustosa'' is commonly mistaken for ''

Russula virescens ''Russula virescens'' is a basidiomycete mushroom of the genus ''Russula'', and is commonly known as the green-cracking russula, the quilted green russula, or the green brittlegill. The species was described as new to science in 1774 by Jacob ...

'', a more desirable edible mushroom that features greenish patches on its cap surface. The latter species has flesh that breaks apart more readily, and a white spore print.

Ecology and distribution

''Russula crustosa'' is a

mycorrhiza A mycorrhiza (; , mycorrhiza, or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, the plant root system and its surroundings. Mycorrhizae play ...

l fungus and associated with broadleaf trees, particularly

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

and

hickory Hickory is a common name for trees composing the genus ''Carya'', which includes 19 species accepted by ''Plants of the World Online''. Seven species are native to southeast Asia in China, Indochina, and northeastern India (Assam), and twelve ...

. The fruit bodies grow on the ground in

mixed forest 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 ...

s singly, scattered, or in groups. Fruiting occurs between June and December. The

pleasing fungus beetle file:Ischyrus quadripunctatus P1390172a.jpg, ''Ischyrus quadripunctatus'' Erotylidae, or the pleasing fungus beetles, is a family (biology), family of beetles belonging to Cucujoidea containing over 100 genus, genera. In the present circumscrip ...

species '' Tritoma angulata'' is known to feed on the fruit bodies. In North America, the mushroom is common, and widespread in the southeastern United States. In Asia, ''Russula crustosa'' is found in China, India, Malaysia, and Thailand.

References

External links