A cystidium (plural cystidia) is a relatively large cell found on the sporocarp of a

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, Bas ...

(for example, on the surface of a

mushroom 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. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is ...

gill), often between clusters of

basidia A basidium () is a microscopic sporangium (a spore-producing structure) found on the hymenophore of fruiting bodies of basidiomycete fungi which are also called tertiary mycelium, developed from secondary mycelium. Tertiary mycelium is highly- ...

. Since cystidia have highly varied and distinct shapes that are often unique to a particular species or genus, they are a useful micromorphological characteristic in the identification of basidiomycetes. In general, the adaptive significance of cystidia is not well understood.

Classification of cystidia

By position

Cystidia may occur on the edge of a lamella (or analogous hymenophoral structure) (cheilocystidia), on the face of a lamella (pleurocystidia), on the surface of the cap (dermatocystidia or pileocystidia), on the margin of the cap (circumcystidia) or on the stipe (caulocystidia). Especially the pleurocystidia and cheilocystidia are important for identification within many genera. Sometimes the cheilocystidia give the gill edge a distinct colour which is visible to the naked eye or with a hand lens.

By morphology

Chrysocystidia are cystidia whose contents contain a distinct refractive yellow body, that becomes more deeply yellow when exposed to

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous ...

or other

alkaline In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...

compounds. Chrysocystidia are characteristic of many (though not all) members of the

agaric An agaric () is a type of fungus 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. In the UK, agarics are called "mushroom ...

family

Strophariaceae The Strophariaceae are a family of fungi in the order Agaricales. Under an older classification, the family covered 18 genera and 1316 species. The species of Strophariaceae have red-brown to dark brown spore prints, while the spores themselves a ...

. Gloeocystidia have an oily or granular appearance under the microscope. Like

gloeohypha 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 or ...

e, they may be yellowish or clear (

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

) and can sometimes selectively be coloured by sulphovanillin or other reagents.Moser M (translated by S Plant). 1983. ''Keys to Agarics and Boleti''. Roger Phillips. . Metuloids are thick-walled cystidia with an apex having any of several distinct shapes.Largent D, et al. 1977. ''How to Identify Mushrooms to Genus III: Microscopic Features''. Arcata, CA: Mad River Press. .

External links

BCERN Glossary: Cystidia

* ttp://www.ne.jp/asahi/mushroom/tokyo/Inocybe/kobuasetake/kobuasetake.htm Wild Mushrooms from Tokyo: Inocybe nodulososporaIncludes very good photograph of cystidia.

References

{{reflist Fungal morphology and anatomy