An ascocarp, or ascoma (), is the fruiting body (
sporocarp) of an
ascomycete phylum fungus. It consists of very tightly interwoven
hyphae and millions of embedded
asci, each of which typically contains four to eight
ascospore
An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or ...
s. Ascocarps are most commonly bowl-shaped (apothecia) but may take on a spherical or flask-like form that has a pore opening to release spores (perithecia) or no opening (cleistothecia).
Classification
The ascocarp is classified according to its placement (in ways not fundamental to the basic
taxonomy
Taxonomy is the practice and science of categorization or classification.
A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
). It is called ''epigeous'' if it grows above ground, as with the
morels, while underground ascocarps, such as
truffles
A truffle is the fruiting body of a subterranean ascomycete fungus, predominantly one of the many species of the genus ''Tuber''. In addition to ''Tuber'', many other genera of fungi are classified as truffles including '' Geopora'', '' Pe ...
, are termed ''hypogeous''. The structure enclosing the
hymenium is divided into the types described below (apothecium, cleistothecium, etc.) and this character ''is'' important for the taxonomic classification of the fungus. Apothecia can be relatively large and fleshy, whereas the others are microscopic—about the size of flecks of ground pepper.
Apothecium
An apothecium (plural: apothecia) is a wide, open, saucer-shaped or cup-shaped fruit body. It is sessile and fleshy. The structure of the apothecium chiefly consists of three parts: ''
hymenium'' (upper concave surface), ''hypothecium'', and ''excipulum'' (the "foot"). The asci are present in the hymenium layer. The asci are freely exposed at maturity. An example are the members of ''Dictyomycetes''. Here the fertile layer is free, so that many spores can be dispersed simultaneously. The
morel, ''Morchella'', an edible ascocarp, not a mushroom, favored by gourmets, is a mass of apothecia fused together in a single large structure or cap. The genera ''
Helvella'' and ''
Gyromitra
''Gyromitra'' () is a genus of about 18 species of ascomycete fungi. They are a false morel - a frequently toxic mushroom that can be mistaken for edible mushrooms of the genus ''Morchella'' (morels).
Taxonomy
The name ''Gyromitra'' comes from ...
'' are similar.
Cleistothecium
A cleistothecium (plural: cleistothecia) is a globose, completely closed fruit body with no special opening to the outside. The ascomatal wall is called ''
peridium
The peridium is the protective layer that encloses a mass of spores in fungi. This outer covering is a distinctive feature of gasteroid fungi.
Description
Depending on the species, the peridium may vary from being paper-thin to thick and rubbe ...
'' and typically consists of densely interwoven hyphae or ''pseudoparenchyma'' cells. It may be covered with hyphal outgrowth called ''appendages''. The asci are globose, deliquescent, and scattered throughout the interior cavity i.e. as in ''Eurotium'' or arising in tufts from the basal region of ascocarps as in ''Erysiphe''. In this case the ascocarp is round with the hymenium enclosed, so the spores do not automatically get released, and fungi with cleistothecia have had to develop new strategies to disseminate their spores. The truffles, for instance, have solved this problem by attracting animals such as
wild boar
The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species is ...
s, which break open the tasty ascocarps and spread the spores over a wide area. Cleistothecia are found mostly in fungi that have little room available for their ascocarps, for instance those that live under tree bark, or underground like truffles.
Gymnothecium
Similar to a cleistothecium, a gymnothecium is a completely enclosed structure containing globose or pear-shaped, deliquescent asci. However, unlike the cleistothecium, the peridial wall of a gymnothecium consists of a loosely woven "tuft" of hyphae, often ornamented with elaborate coils or spines. Examples are the ''
Gymnoascus
''Gymnoascus'' is a genus of fungi within the Gymnoascaceae family. The genus, widely distributed in northern temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), whic ...
'', ''
Talaromyces
''Talaromyces'' is a genus of fungi in the family Trichocomaceae. Described in 1955 by American mycologist Chester Ray Benjamin, species in the genus form soft, cottony fruit bodies (ascocarps) with cell walls made of tightly interwoven hypha
...
'' and the
dermatophyte
Dermatophyte (from Greek '' derma'' "skin" ( GEN ''dermatos'') and ''phyton'' "plant") is a common label for a group of fungus of ''Arthrodermataceae'' that commonly causes skin disease in animals and humans. Traditionally, these anamorphic (a ...
''
Arthroderma''.
Perithecium
Perithecia are flask shaped structures opening by a pore or ''
ostiole'' (short papilla opening by a circular pore) through which the ascospores escape. The ''ostiolar canal'' may be lined by hair-like structures called ''periphyses''. The unitunicate asci are usually cylindrical in shape, borne on a stipe (stalk), released from a pore, developed from the inner wall of the perithecium and arise from a basal plectenchyma-centrum. Examples are members of
Sphaeriales and
Hypocreales. Perithecia are also found in ''
Xylaria
''Xylaria'' is a genus of ascomycetous fungi commonly found growing on dead wood. The name comes from the Greek ''xýlon'' meaning ''wood'' (see xylem).
Two of the common species of the genus are ''Xylaria hypoxylon'' and '' Xylaria polymorp ...
'' (Dead Man's Fingers, Candle Snuff), ''
Nectria'', ''
Claviceps'' and ''
Neurospora
''Neurospora'' is a genus of Ascomycete fungi. The genus name, meaning "nerve spore" refers to the characteristic striations on the spores that resemble axons.
The best known species in this genus is '' Neurospora crassa'', a common model organ ...
''.
Sometimes the perithecia are "free" (individually visible from the outside), but in many species they are embedded in a dense sterile tissue of haploid cells called a ''stroma'' (plural: stromata).
[See page 30 and glossary of ]
Pseudothecium
This is similar to a perithecium, but the asci are not regularly organised into a hymenium and they are
bitunicate, having a double wall that expands when it takes up water and shoots the enclosed spores out suddenly to disperse them. Example species are
Apple scab
Apple scab is a common disease of plants in the rose family (Rosaceae) that is caused by the ascomycete fungus ''Venturia inaequalis''. While this disease affects several plant genera, including ''Sorbus, Cotoneaster,'' and ''Pyrus'', it is mos ...
(''Venturia inaequalis'') and the horse chestnut disease ''
Guignardia
''Guignardia'' is a genus of fungi in the family Botryosphaeriaceae.
The genus name of ''Guignardia'' is in honour of Jean Louis Léon Guignard (1852–1928), who was a French pharmacist and botanist.
The genus was circumscription (taxonomy), c ...
aesculi''.
See also
*
Basidiocarp
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 ...
*
Conidium
A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to th ...
References
{{Fungus
Mycology
Fungal morphology and anatomy
de:Schlauchpilze#Das Ascokarp