Partial veil
Encyclopedia
Partial veil is a mycological
term used to describe a temporary structure of tissue found on the fruiting bodies of some basidiomycete
fungi
, typically agarics
. Its role is to isolate and protect the developing spore-producing surface
, represented by gills or tubes, found on the lower surface of the cap
. A partial veil, in contrast to a universal veil
, extends from the stem
surface to the cap
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. The term partial veil is synonymous with inner veil (to differentiate it from the "outer", or universal veil), or velum.
of some basidiomycete 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. 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
, are known as cortinas. The fibrous threads of the cortina often catch the brown spore
s as they drop, making them visible as fine brown streaks along the stem. Some species of Agaricus
, such as Agaricus arvensis
, have a partial veil that resembles a cogwheel. Mycologists Alexander H. Smith
and Harry D. Thiers
, in their 1964 monograph
on the bolete
genus Suillus
, 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.
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
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
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
.
Mycology
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicinals , food and entheogens, as well as their dangers, such as poisoning or...
term used to describe a temporary structure of tissue found on the fruiting bodies of some basidiomycete
Basidiomycota
Basidiomycota is one of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya within the Kingdom Fungi...
fungi
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...
, typically agarics
Agaric
An agaric is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe , with lamellae on the underside of the pileus. "Agaric" can also refer to a basidiomycete species characterized by an agaric-type fruiting body...
. Its role is to isolate and protect the developing spore-producing surface
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 others some cells develop into sterile cells called cystidia or...
, represented by gills or tubes, found on the lower surface of 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...
. A partial veil, in contrast to a 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...
, extends from 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...
surface to 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...
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
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...
, or fragments attached to the stem or cap edge. In some mushrooms, both a partial veil and a universal veil may be present. The term partial veil is synonymous with inner veil (to differentiate it from the "outer", or universal veil), or velum.
Structure
In the immature fruit bodiesBasidiocarp
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...
of some basidiomycete 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. 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
Cortinarius is a genus of mushrooms. It is suspected to be the largest genus of agarics, containing over 2000 different species and found worldwide. A common feature among all species in the genus Cortinarius is that young specimens have a cortina between the cap and the stem, hence the name,...
, are known as cortinas. The fibrous threads of the cortina often catch the brown 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 as they drop, making them visible as fine brown streaks along the stem. Some species of Agaricus
Agaricus
Agaricus is a large and important genus of mushrooms containing both edible and poisonous species, with possibly over 300 members worldwide...
, such as Agaricus arvensis
Agaricus arvensis
Agaricus arvensis, commonly known as the Horse Mushroom, is a mushroom of the genus Agaricus.-Taxonomy:Described as Agaricus arvensis by Jacob Christian Schaeffer in 1762, and given numerous binomial descriptions since. Its present name arvensis means 'of the field'.-Description:The cap is similar...
, have a partial veil that resembles a cogwheel. Mycologists Alexander H. Smith
Alexander H. Smith
Alexander Hanchett Smith was an American mycologist known for his extensive contributions to the taxonomy and phylogeny of the higher fungi, especially the agarics.-Early life:...
and Harry D. Thiers
Harry D. Thiers
Harry Delbert Thiers, born January 22, 1919 in Fort McKavett, Texas, died August 8, 2000 in Ohio, was an American mycologist who studied and named a great many fungi of native to North America, particularly California. Thiers taught mycology at San Francisco State University for many years, and a...
, in their 1964 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...
on the bolete
Bolete
A bolete is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe, with a spongy surface of pores on the underside of the pileus...
genus Suillus
Suillus
Suillus is a genus of basidiomycete fungi in the family Suillaceae and order Boletales. Species in the genus are associated with coniferous trees, and are mostly distributed in northern temperate locations, although some species have been introduced to the Southern Hemisphere.-Taxonomy:The genus...
, 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. In the early 20th century, American mycologist George F. Atkinson investigated the development of the mushroom Agaricus arvensisAgaricus arvensis
Agaricus arvensis, commonly known as the Horse Mushroom, is a mushroom of the genus Agaricus.-Taxonomy:Described as Agaricus arvensis by Jacob Christian Schaeffer in 1762, and given numerous binomial descriptions since. Its present name arvensis means 'of the field'.-Description:The cap is similar...
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
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 others some cells develop into sterile cells called cystidia or...
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
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 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
Agaricus augustus
Agaricus augustus, known commonly as the prince, is a basidiomycete fungus of the genus Agaricus.-Taxonomy:According to Heinemann's popular division of Agaricus, A. augustus belongs to section Arvenses. The system proposed by Wasser classifies A. augustus within subgenus Flavoagaricus, section...
.