1797-09-03 Agaricus campestris Plate by James Sowerby

mycology Mycology is the branch of biology concerned with the study of fungus, fungi, including their Taxonomy (biology), taxonomy, genetics, biochemistry, biochemical properties, and ethnomycology, use by humans. Fungi can be a source of tinder, Edible ...

, a partial veil (also called an inner veil, to differentiate it from the "outer", or

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 sph ...

) is a temporary structure of tissue found on the fruiting bodies of some

basidiomycete Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basid ...

fungi 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 ...

, typically

agaric An agaric () is a type of fungal fruiting body characterized by the presence of a pileus (cap) that is clearly differentiated from the stipe (stalk), with lamellae (gills) on the underside of the pileus. It is a type of mushroom (or toadstool) ...

s. Its role is to isolate and protect the developing spore-producing surface, represented by

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 ...

or tubes, found on the lower surface of 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. The origin of the word "cap" comes from the Old French word "chapeau" which means "head co ...

. A partial veil, in contrast to a universal veil, extends from the

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

surface to the

edge. The partial veil later disintegrates, once the fruiting body has matured and the spores are ready for dispersal. It might then give rise to a stem ring, or fragments attached to the stem or cap edge. In some mushrooms, both a partial veil and a universal veil may be present.

Structure

In the immature

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 ...

of some

fungi, the partial veil extends from the stem surface to the cap margin and shields the gills during development, and later breaks to expose the mature gills. The presence, absence, or structure of the partial veil is an aid to identification of mushrooms.Arora (1986), p. 16. Some fruit bodies may have both a universal and partial veil, others may have only one or the other, while many lack both types of veils. The partial veil may be membranous or cobwebby, and may have multiple layers. Various adjectives are commonly used to describe the texture of partial veils, such as: ''membranous'', like a membrane; ''cottony'', where the veil tissue is made of separate fibers that may be easily separated like a cotton ball; ''fibrillose'', composed of thin strands and ''glutinous'', with a slimy consistency. Some mushrooms have partial veils which are ''evanescent'', which are so thin and delicate that they disappear after they rupture, or leave merely a faint trace on the stem known as an ''annular zone'' or ''ring zone''. Others may leave a persistent annulus (ring). Occasionally, the partial veil adheres to the edge of the cap as shreds of tissue, forming an ''appendiculate'' margin. The cobweb-like, fragile partial veil of some mushrooms, especially those in the genus ''

Cortinarius ''Cortinarius'' is a globally distributed genus of fungus in the family Cortinariaceae. Its members are commonly known by the names cortinar and webcap. It is suspected to be the largest genus of agarics, containing over 2,000 widespread species ...

'', are known as ''cortinas''. The fibrous threads of the cortina often catch the brown

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 as they drop, making them visible as fine brown streaks along the stem. Some species of ''

Agaricus ''Agaricus'' is a genus of mushroom-forming fungi containing both edible and poisonous species, with over 400 members worldwide and possibly again as many disputed or newly discovered species. The genus includes the common ("button") mushroom ...

'', such as ''

Agaricus arvensis ''Agaricus arvensis'', commonly known as the horse mushroom, is a mushroom-forming fungus of the genus ''Agaricus''. Taxonomy It was described as ''Agaricus arvensis'' by Jacob Christian Schaeffer in 1774, and given numerous binomial descript ...

'', have a partial veil that resembles a

cogwheel A gear or gearwheel is a rotating machine part typically used to transmit rotational motion and/or torque by means of a series of teeth that engage with compatible teeth of another gear or other part. The teeth can be integral saliences or ...

. Mycologists Alexander H. Smith and Harry D. Thiers, in their 1964

monograph A monograph is generally a long-form work on one (usually scholarly) subject, or one aspect of a subject, typically created by a single author or artist (or, sometimes, by two or more authors). Traditionally it is in written form and published a ...

on the

bolete A bolete is a type of mushroom, or fungal fruiting body. It can be identified thanks to a unique cap. On the underside of the cap there is usually a spongy surface with pores, instead of the gills typical of mushrooms. A similar pore surface i ...

genus ''

Suillus ''Suillus'' is a genus of basidiomycete fungi in the family Suillaceae and order Boletales. Species in the genus are associated with trees in the pine family (Pinaceae), and are mostly distributed in temperate locations in the Northern Hemisphe ...

'', proposed the term "false veil" to account for those species of ''Suillus'' that have a "conspicuous cottony roll" of tissue that originates from the cap margin (especially in young specimens) and never becomes integrated with the stem tissue.

Development in ''Agaricus''

Species in the genus ''Agaricus'' have a partial veil that is made of two layers of tissue, although the two layers are not clearly distinct in all species.Arora, 1986, p. 312. In the early 20th century, American mycologist

George Francis Atkinson George Francis Atkinson (January 26, 1854 – November 14, 1918) was an American botanist and mycologist.Makers of American Botany, Harry Baker Humphrey, Ronald Press Company, Library of Congress Card Number 61-18435 He was born on January 26, ...

investigated the development of the mushroom ''

'' by collecting young mushroom buttons (immature fruit bodies with the veil intact and the cap not yet expanded) and observing their growth in the laboratory. He determined that the partial veil originates from the tissue lying outside the annular cavity (the area containing the delicate developing

hymenium The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in oth ...

and enclosed by the partial veil) and is not clearly separated from the universal veil. It is connected to both the margin of the cap and the surface of the stem. The partial veil increases in size as tension is applied to it from the expansion of the cap and stem. The lower portion of the partial veil (connected to the stem) has a looser texture, and is relatively porous to allow for air exchange. The upper portion of the partial veil (next to the gill cavity) is connected directly with the margin of the cap. It originates partly from fundamental tissue (actively dividing

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 o ...

e that comprise the bulk of the cap and stem tissue) and partly by growth from the margin of the cap. The looser portion of the veil is torn off from the surface of the stem as the mushroom expands and grows, and provides the looser lower portion of the duplex veil characteristic of this species and some of the other species of ''Agaricus'', like '' A. augustus''.

Gallery

File:Cortinarius claricolor 01.jpg, A cobweb-like cortina of ''

Cortinarius claricolor ''Cortinarius'' is a globally distributed genus of fungus in the family Cortinariaceae. Its members are commonly known by the names cortinar and webcap. It is suspected to be the largest genus of agarics, containing over 2,000 widespread specie ...

'' File:Basidioma agaric veils.png, A simplified diagram of an agaric-type basidioma in (A) the early development stage, and (B) after the body is fully expanded. (1) is the

, the outer layer protecting the developing basidioma; (2) is the partial veil, which covers the gills; (3) are cap scales, remnants of the universal veil; (4) is the volva, another remnant of the universal veil, but at the base of the basidioma; (5) is the annulus, a ring-like mark on the stipe that is a remnant of the partial veil, and whose overhanging tissue may become a cortina in some mushrooms.

Structure

Development in ''Agaricus''

Gallery

See also