''Annulohypoxylon annulatum'' is a pyrenomycete, a carbonaceous

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 ...

that produces its

ascospores In fungi, an ascospore is the sexual spore formed inside an ascus—the sac-like cell that defines the division Ascomycota, the largest and most diverse division of fungi. After two parental nuclei fuse, the ascus undergoes meiosis (halving of ...

perithecia An ascocarp, or ascoma (: ascomata), 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 ascospores. Ascoc ...

(flask shaped container), and then shoots them out through an opening called the

ostiole An ''ostiole'' is a small hole or opening through which algae or fungi release their mature spores. The word is a diminutive of wikt:ostium, "ostium", "opening". The term is also used in higher plants, for example to denote the opening of the ...

. ''

Annulohypoxylon ''Annulohypoxylon'', sometimes called cramp balls, is a genus of fungi in the family Xylariaceae. The 27 species in the genus have a collectively widespread distribution. The genus ''Annulohypoxylon'' was created in 2005 and contains species for ...

'' was derived from the original

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Hypoxylon ''Hypoxylon'' is a genus of ascomycetes commonly found on dead wood, and usually one of the earliest species to colonise dead wood. A common European species is ''Hypoxylon fragiforme'' which is particularly common on dead trunks of beech. Based ...

'' in 2005 and is distinguished by their flat, disk-like rings encircling the ostioles (hence the annulo- prefix). The

stromata The ''Stromata'' (), a mistake for ''Stromateis'' (Στρωματεῖς, "Patchwork," i.e., ''Miscellanies''), attributed to Clement of Alexandria (c. 150 – c. 215), is the third of a trilogy of works regarding the Christian life. The oldest ...

(fruiting bodies) of ''A. annulatum'' are semi-globose to cushion-like and are black in color. They are covered in ostioles (pimple-like in appearance) surrounded by a flat disc area. A

hand lens A magnifying glass is a convex lens—usually mounted in a frame with a handle—that is used to produce a magnification, magnified image of an object. A magnifying glass can also be used to focus light, such as to concentrate the Sun's radiati ...

may be needed in order to see this. This species commonly grows on

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 when crushed and mixed with

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

will produce an olive green pigment. Microscopically, "ascospores brown to dark brown, ellipsoid-inequilateral, 7.5–12 × 3.5–5

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 ...

, with straight

germ slit A germ pore is a small pore in the outer wall of a fungal spore through which the germ tube exits upon germination. It can be apical or eccentric in its location, and, on light microscopy, may be visualized as a lighter coloured area on the cell ...

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 ...

-length".

References

Xylariales Fungi described in 1825 Taxa named by Lewis David de Schweinitz Fungus species {{Xylariales-stub