Mushrooms

 

Section Overview

Overview of Mushrooms

 

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Humans and Mushrooms

 

Section Overview

 

Along with lichens, mushrooms are a conspicious and significant com-

ponent of the ecology of Sky Meadows State Park; however, they have

not been systemically studied. Future research into the various mush-

room species inhabiting the park needs to be conducted.

 

Overview of Mushrooms

 

The following is an edited version of the Wikipedia entry for "Mush-

rooms".

 

A mushroom (or toadstool) is the fleshy, spore-bearing fruiting body

of a fungus, typically produced above ground on soil or on its food

source. The standard for the name "mushroom" is the cultivated white

button mushroom, Agaricus bisporus; hence the word "mushroom" is

most often applied to those fungi (Basidiomycota, Agaricomycetes)

that have a stem (stipe), a cap (pileus), and gills (lamellae) or pores

on the underside of the cap. These pores or gills produce microscopic

spores that help the fungus spread across the ground or its occupant

surface.

 

"Mushroom" describes a variety of gilled fungi, with or without stems,

and the term is used even more generally, to describe both the fleshy

fruiting bodies of some Ascomycota and the woody or leathery fruit-

ing bodies of some Basidiomycota, depending upon the context of the

word.

 

Forms deviating from the standard morphology usually have more spe-

cific names, such as "puffball", "stinkhorn", and "morel", and gilled

mushrooms themselves are often called "agarics" in reference to their

similarity to Agaricus or their place Agaricales. By extension, the term "mushroom" can also designate the entire fungus when in culture; the

thallus (called a mycelium) of species forming the fruiting bodies called mushrooms; or the species itself.

 

While modern identification of mushrooms is quickly becoming molecular,

the standard methods for identification are combined with microscopic examination. The presence of juices upon breaking, bruising reactions,

odors, tastes, shades of color, habitat, habit, and season are all considered

by both amateur and professional mycologists. Tasting and smelling mush-

rooms carries its own hazards because of poisons and allergens. Chemical

tests are also used for some genera. In general, identification to genus can

often be accomplished in the field using a local mushroom guide. Identifi-

cation to species, however, is more problematic; it must be remembered

that a mushroom develops from a button stage into a mature structure, and

only the latter can provide certain characteristics needed for the identifica-

tion of the species.

 

Morphology: A mushroom develops from a nodule, or pinhead, less than

two millimeters in diameter, called a primordium, which is typically found

on or near the surface of the substrate. It is formed within the mycelium,

the mass of threadlike hyphae that make up the fungus. The primordium

enlarges into a roundish structure of interwoven hyphae roughly resembl-

ing an egg, called a "button". The button has a cottony roll of mycelium,

the universal veil, that surrounds the developing fruit body. As the egg

expands, the universal veil ruptures and may remain as a cup, or volva, at

the base of the stalk, or as warts or volval patches on the cap. Many mush-

rooms lack a universal veil, therefore they do not have either a volva or

volval patches. Often, a second layer of tissue, the partial veil, covers the

bladelike gills that bear spores. As the cap expands, the veil breaks, and

remnants of the partial veil may remain as a ring, or annulus, around the

middle of the stalk or as fragments hanging from the margin of the cap.

The ring may be skirt-like as in some species of Amanita, collar-like as in

many species of Lepiota, or merely the faint remnants of a cortina (a par-

tial veil composed of filaments resembling a spiderweb), which is typical

of Genus Cortinarius. Mushrooms lacking partial veils do not form an

annulus.

 

The stalk (also called the stipe, or stem) may be central and support the

cap in the middle, or it may be off-center and/or lateral, as in species of

Pleurotus and Panus. In other mushrooms, a stalk may be absent, as in the polypores that form shelf-like brackets. Puffballs lack a stalk, but may

have a supporting base. Other mushrooms, such as truffles, jellies, earth-

stars, and bird's nests, usually do not have stalks, and a specialized myco-

logical vocabulary exists to describe their parts.

 

The way the gills attach to the top of the stalk is an important feature of

mushroom morphology. Mushrooms in Genera Agaricus, Amanita, Lepiota

and Pluteus, among others, have free gills that do not extend to the top of

the stalk. Others have decurrent gills that extend down the stalk, as in Gen-

era Omphalotus and Pleurotus. There are a great number of variations bet-

ween the extremes of free and decurrent, collectively called attached gills.

Finer distinctions are often made to distinguish the types of attached gills:

adnate gills, which adjoin squarely to the stalk; notched gills, which are

notched where they join the top of the stalk; adnexed gills, which curve up-

ward to meet the stalk, and so on. These distinctions between attached gills

are sometimes difficult to interpret, since gill attachment may change as

the mushroom matures, or with different environmental conditions.

 

Growth: Many species of mushrooms seemingly appear overnight, grow-

ing or expanding rapidly. This phenomenon is the source of several com-

mon expressions in the English language including "to mushroom" or "mushrooming" (expanding rapidly in size or scope) and "to pop up like a mushroom" (to appear unexpectedly and quickly). In reality all species of mushrooms take several days to form primordial mushroom fruit bodies,

though they do expand rapidly by the absorption of fluids.

 

The cultivated mushroom as well as the common field mushroom initially

form a minute fruiting body, referred to as the pin stage because of their

small size. Slightly expanded they are called buttons, once again because

of the relative size and shape. Once such stages are formed, the mushroom

can rapidly pull in water from its mycelium and expand, mainly by inflat-

ing preformed cells that took several days to form in the primordia.

 

Similarly, there are even more ephemeral mushrooms, like Parasola pli-

catilis (formerly Coprinus plicatlis), that literally appear overnight and

may disappear by late afternoon on a hot day after rainfall. The primordia

form at ground level in lawns in humid spaces under the thatch and after

heavy rainfall or in dewy conditions balloon to full size in a few hours,

release spores, and then collapse. They "mushroom" to full size.

 

Not all mushrooms expand overnight; some grow very slowly and add tis-

sue to their fruitbodies by growing from the edges of the colony or by in-

serting hyphae. For example Pleurotus nebrodensis grows slowly, and be-

cause of this combined with human collection, it is now critically endanger-

ed.

 

Though mushroom fruiting bodies are short-lived, the underlying mycelium

can itself be long-lived and massive. A colony of Armillaria solidipes (form-

erly known as Armillaria ostoyae) in Malheur National Forest in the United

States is estimated to be 2,400 years old, possibly older, and spans an esti-

mated 2,200 acres (8.9 km2). Most of the fungus is underground and in

decaying wood or dying tree roots in the form of white mycelia combined

with black shoelace-like rhizomorphs that bridge colonized separated woody substrates.

 

It has been suggested the electrical stimulus of a lightning bolt striking

mycelia in logs accelerates the production of mushrooms.

 

 

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