Glossary of Fungi (Molds) and Fungal Terms

This glossary was created and supplied courtesy of Air Quality Sciences (AQS).  

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, X, Y, Z

A

Acremonium - genus that has the spore bearing cells directly on the hypha, which bear single celled spores. Some species produce spores in a slime drop and some in dry chains. Some experts put the species that produce spores in chains in the genus Gliomastix. Acremonium spp. are generally considered soil fungi, and some species can grow indoors when damp conditions are present.

Alternaria - genus characterized by large, darkly pigmented spores with longitudinal and transverse septa. Spores are produced in chains from simple conidiophores and may bulge slightly between septa. Spores typically have one cell that extend out from the body of the spore, appearing as a "beak". There are many species that are specialized plant pathogens and a few species that are common spoilage molds. Alternaria is common in outdoor air (also see Stemphylium and Ulocladium).

anamorph - the part of a life cycle (or spore state) of a fungal species that produces asexual (or imperfect) spores. These states, or morphs, of a species often have a different name than the teleomorph (or sexual) state of the fungus.

annellophore - refers to a type of fertile cell on hyphomycete conidiophores. Annellophores are flask shaped, and conidia (spores) are extruded through a neck that lengthens as more cells are produced; characteristic annular "rings" develop on the annellophore neck for each conidium products (see also phialides).

Arthrinium - genus characterized by one celled, round, pigmented conidia, having a distinct germ slit and occurring in clusters. Species of this genus are widely distributed saprobes on dead plant material, particularly in swampy habitats. Their occurrence in soil is secondary. Arthrinium is mainly recovered from outdoor air.

ascoma - sexual fruiting body of an ascomycete.

ascomycete - fungus that produces spores in an ascus; pink bread mold is a common ascomycete. Most of the common molds encountered indoors are asexual states of ascomycetes.

ascospores - spores that are produced in an ascus, which are characteristic of ascomycetes.

ascus (pl. asci) - a specialized, characteristic cell that produces the sexual spores of ascomycetes.

Aspergillus - large genus of fungi characterized by spore bearing structures resembling an aspergillum ("sprinkler" used by Roman Catholic priests for holy water). Aspergilllus species are common in most environments. Many species are soil fungi, some species are very important biodeteriogen agents and some species are infectious, primarily to individuals with weakened or compromised immune systems. Some species can produce very potent mycotoxins. Some Aspergillus species are extreme xerophiles and multiply in dust of buildings with high humidity.

B

basidiomycete - fungus that produces spores on a basidium. Mushrooms and wood decay fungi are common types of basidiomycetes.

basidiospores - spores that are produced on basidia; these are characteristic of basidiomycetes.

basidium (pl. basidia) - a cell which produces the sexual spores of basidiomycetes; characteristic of basidiomycetes.

Beauveria - genus that occur in soil and are also parasites of arthropods, especially insects.

Bipolaris - see Drechslera.

biverticillate - (bivert) species of Penicillium that have condiophores with one level of branching beneath the phialides (literally two verticels). Many of these species are soil fungi; some are important food spoilage molds and biodeteriogens.

C

cellulolytic - ability to break down, or degrade cellulose and cellulose-based materials. Cellulolytic fungi typically digest the cellulose as a source of nutrients. Avery large number of fungi are cellulolytic

Chaetomium - genus of ascomycete fungi characterized by a fruiting body almost completely enclosed and covered with pigmented hairs. Many species are soil fungi, and some species are well known for their ability to rapidly digest cellulose-based materials. Some species can produce soft rot in wood. Chaetomium can be found indoors on water damaged cellulose-based materials such as the paper facing of wet gypsum wallboard.

chlamydospores - a fungal propagule produced as a differentiated hyphal cell.

Cladosporium - genus characterized by darkly pigmented spores produced in chains from branched conidiophores. Cladosporium spores may be single celled or septate. There are many species in this genus, and several species are common in outdoor air. Cladosporium spp. are usually the single most abundant type of mold in outdoor air; some are also common on painted wooden surfaces and may grow indoors.

clamp connection - specialized bridge over a hyphal septum in some basidiomycetes. These structures only occur in some basidiomycetes.

colony - a growing portion of fungus that is visible to the unaided eye and is discrete from other areas of fungal growth

colony forming unit (CFU) - part of a fungus that can form a growing colony when placed on a suitable culture medium. A CFU can be either a single spore, a cluster of spores that produces a single colony, or hyphae that are able to initiate (or continue) growth into a colony.

conidial fungi - (hyphomycetes, deuteromycetes, imperfect fungi, Fungi Imperfecti) a large and very diverse group of mostly asexual ascomycete fungi. Most of the common "molds" and "mildews" encountered in everyday life are conidial fungi.

conidium (pl. conidia) - term used for asexual spores that are produced externally on hyphal structures, in contrast to asexual spores that are produced inside a differentiated structure (cf sporangiospores).

conidiophore - differentiated hyphal structure that produces asexual spores on the outside of the conidiophore (i.e not in an enclosed structure such as a sporangium). The conidiogenous cells on condiophores are the specific cells that produce conidia. There are various types of condiogenous cells that are often characteristic of the particular fungal genus; phialides and annellophores are types of condiogenous cells.

Curvularia - genus having multiseptate, darkly pigmented conidia with the middle cell enlarged on one side so that the spore is slightly curved. Many of the species are plant pathogens, but some are saprobes. This genus occurs commonly in outdoor air.

D

dematiaceous - having a brown or black pigment (melanin) in the cell wall of the hyphae or conidia. Darkly pigmented.

Drechslera - genus having darkly pigmented, multiseptate conidia with thick walls and very thick septa. These are mostly leaf spot pathogens, and are common in outdoor air. The conidia of Exserohilum, Bipolaris (both also leaf spot pathogens) and Drechslera are similar and formerly were all classified as Helminthosporium. These spore types frequently are counted together in spore trap analyses due to their similar morphology.

E

Emericella - genus of ascomycete fungi that have Aspergillus anamorphs; for example, Emericella (Aspergillus) nidulans and E. variecolor.

Epicoccum - genus having very large, rough, thick-walled conidia formed directly on the hyphae; this is a phylloplane (leaf-surface type) mold that also sometimes occurs on water damaged building surfaces, such as wallboard.

Eurotium - teleomorphic (sexual state) stage of the genus Aspergillus. Generally xerotolerant to xerophilic.

Exserohilum - see Drechslera.

F

fruiting body - any of a variety of structures that produce spores. Presence on tape lifts indicates the surface was colonized.

Fusarium - genus of conidial fungi found predominantly in seeds or occurring as a plant pathogen, and occasionally as a saprobe on decaying organic matter. Most are important plant pathogens, and some are saprobes. Many species produce mycotoxins. Several species produce potent trichothecene mycotoxins.

fungus (pl. fungi) - one of a large group of organisms including molds, mildews, mushrooms, yeasts and many plant parasites. These are typically multicellular organisms with a filamentous habit, and may live as a parasite, a facultative pathogen or as a saprobe. These are important decomposers in most ecosystems.

G

Ganoderma - genus of basidiomycetes that are important wood decay fungi and tree pathogens (including artist's conk). The basidiospores of Ganoderma are distinctive and can be readily identified on spore traps and may be identifiable on cellotape samples.

Gliomastix - genus of conidial fungi having the spore bearing cells directly on the hyphae and producing pigmented, single celled spores in chains. Some experts consider Gliomastix to be dry-spored species of Acremonium.

globose - shaped like a globe.

H

hyaline - colorless or not darkly pigmented.

Helminthosporium - see Drechslera.

holomorph - complete or "whole" form of a fungus including all parts of the life cycle.

hülle cells - specialized cells that are produced by some species of Aspergillus and Emericella. Masses of hülle cells comprise the wall of the sexual fruiting structure (ascoma) of Emericella.

hypha (pl. hyphae) filament or thread of fungal cells; the basic unit of the body of fungi (excluding yeasts).

I

No entries.

J

No entries.

K

No entries.

L

No entries.

M

Memnoniella - genus having a conidiophore similar to Stachybotrys, but producing spores in dry chains rather than in a drop of mucilage; also grows on wet materials with amorphous cellulose and can produce mycotoxins.

mitofungi - see conidial fungi.

monoverticillate Penicillia - (monovert) species of Penicillium that have condiophores with no branching beneath the phialides (literally one verticel). Many of these species are soil fungi; some are biodeteriogens.

mycotoxins - secondary metabolites of fungi that in natural exposures can cause disease in vertebrates. Many fungi produce toxic metabolites that are not considered mycotoxins in the strict sense, although some reports generically refer to all toxic metabolites as mycotoxins.

myxomycete/Periconia/smut - used on spore trap reports. A grouping of three types of spores broadly resembling one another in size, shape, color and surface ornamentation. Myxomycetes are slime molds, which typically occur outdoors, but rarely grow indoors on material that has remained saturated for an extended period. Periconia is a genus of saprobic fungi, typically originating in outdoor air. Smuts are obligate plant parasites, originating in outdoor air, typically from areas of field crops.

N

Nigrospora - genus of fungi found in soil and as saprobes on plant material; characterized by the production of single spores (globose, dematiaceous) at the tips of hyphal branches.

O

obligate - refers to requirement that a fungus must colonize living tissue; that is, it is unable to colonize dead organic matter.

outside / other - a group of genera often reported from spore trap analyses that appear mainly outside, and seasonally. When this group of genera present indoors, it generally indicates penetration of outside air. Examples include Cercospora, Helicomyces, Pestalotia, Spegazzinia and Tetraploa, among others.

P

Pithomyces - soil borne genus common on dead leaves and stems. Found occasionally on paper in indoor environments and on ceiling tiles. P. chartarum produces potent toxins when infecting clover and these toxins are responsible for facial eczema of sheep.

Penicillium - genus with a very large number of species; characterized by a distinctive conidiophore with a branched tip and each tip with spore bearing cells that produce dry spores in chains. Penicillium are soil fungi and some are important biodeteriogens. Some of these species are present in almost all environmental samples, but typically as a mixture of species and as a low percentage of the total. Penicillium may colonize damp or wet materials indoors, and is often present as a greater part of samples from such areas. In these cases, Penicillium spp. in that sample will be mostly of one or a few types. Some species (mostly of "tervert" penicilllia) can produce mycotoxins.

phialide - refers to type of fertile cell on hyphomycete conidiophores. Phialides are flask shaped, and conidia (spores) are extruded through a neck that does not lengthen as more conidia are produced (see also annellophore).

phylloplane - literally "leaf surface"; the natural, or original, habitat for many of the fungi (molds) that are abundant in outdoor air, such as Cladosporium and Epicoccum.

Polythrincium - genus of fungi that are saprobes and plant parasites; typically originate from outdoor air.

Q

No entries.

R

rusts, rust fungi - obligate plant parasites, originating in outdoor air, either from forest or field crop areas.

S

saprobic, saprobes (saprotrophic, or saprophytic) - an organism that obtains nutrients from decomposing dead or senescent organic material.

septum (pl. septa) - plate or sheet of cell wall material that divides two adjacent fungal cells. Portion of cell wall that divides adjacent cells in a hypha or spore. Septa in spores can divide the spore along the length of the spore (longitudinal) or across the width of the spore (transverse).

slime molds - organisms that live as amoebae and feed on bacteria, then reproduce by forming spores similar to those of fungi.

sporangiospore - a spore produced inside a sporangium.

sporangium - a differentiated structure in which asexual spores are produced internally, as opposed to being produced externally on a conidiophore; sporangia are typical among zygomycete fungi such as Rhizopus and Mucor.

spore - commonly used term referring to microscopic reproductive structures, produced by almost all fungi, as well as by ferns, mosses and some algae. General term for differentiated propagules of fungi. Fungal spores may be produced either by meiosis (sexual spores), mitosis (asexual spores) or as a differentiated hyphal cell. Basidiospores and ascospores are types of sexual spores; conidia and sporangiospores are examples of asexual spores, chlamydospores are differentiated hyphal cells.

Stachybotrys - genus characterized by having conidiophores with a cluster of swollen spore bearing cells at the tip, producing spores in a drop of mucilage. The species S. chartarum commonly occurs on wet building materials, especially those with amorphous cellulose, such as paper. Some species can produce potent mycotoxins.

Stemphylium - genus characterized by the production of large, heavily pigmented spores that have longitudinal and transverse septa. These are mostly plant pathogens, although some species grow on paper, occur in soil, etc. In contrast to Alternaria, Stemphylium spores do not typically have a beak. In contrast to Ulocladium, Stemphylium spores may be constricted at the median septum. Overlap occurs among certain of these spore features with Alternaria and Ulocladium (also see Alternaria and Ulocladium).

T

taxon (pl. taxa) - refers to a category (such as species, genus or higher grouping) in a classification scheme. The term also is used in microbial reports to refer to the fungi (or spores) identified, since the taxon identified is the species for some fungi, the genus for some, and even more general groups for other fungi.

teleomorph - (cf holomorph) - the part of a life cycle (or spore state) of a fungal species that produces sexual (or perfect) spores. These states, or morphs, of a species often have a different name than the anamorph (or asexual) state of the fungus.

terverticillate - (tervert) species of Penicillium that have condiophores with two levels of branching beneath the phialides (literally three verticels). Many of these species are important food spoilage molds and biodeteriogens of water damaged or damp building materials. Some of these produce mycotoxins.

Torula - genus characterized by pigmented spores, formed in chains and often septate. Torula occurs widely on dead plant material and is often recovered from soil and outdoor air.

trace - refers to the sample collected with a slit style sampler and deposited onto an adhesive surface in spore trap samples. The trace is generally elongate rectangular with slit samplers and is often visible to the unaided eye due to the deposition of particles, such as spores, pollen, skin scales and other debris.

Trichoderma - genus common in soil and on wet, decaying wood. It is often an indicator of abundant moisture in building materials. Toxins produced by various species include gliotoxin, emodin and trichodermin.

Trichothecium - genus found predominantly in soil and on decaying plant parts.

U

Ulocladium - genus characterized by the production of large, heavily pigmented spores that have longitudinal and transverse septa and are produced on bent (geniculate) conidiophores. Ulocladium has a high water requirement, and can propagate on building materials (also see Alternaria and Stemphylium).

Ustilago - a smut fungus which is an obligate plant parasite.

V

No entries.

W

water activity (aw) - a measure of the amount of unbound water in a material. Water activity governs the ability of microbes to colonize a specific material. Another commonly used moisture measure is the bulk moisture content (%MC), which is the weight of total water in a given weight of material. Since water activity (aw) refers to the amount of water (unbound) that is available for microbial growth, aw is a useful concept for understanding microbial growth in either food or construction materials.

X

xerophilic/xerotolerant - "dry-loving" or "dry-tolerant"; refers to fungi (molds) or other microbes that thrive or tolerate conditions with relatively scarce water. For a mold, the moisture level of fresh bread can be thought of as scarce where the moisture level of salami would be very scarce. DG18 agar is best used for the recovery of zerotolerant organisms.

Y

yeast - a unicellular form of fungi that generally does not produce hyphae and reproduce by budding or fission. Yeasts are sometimes present in situations of chronic moisture.

Z

zygomycete - fungus that produces a zygospore as the sexual spore. These fungi often have large diameter hyphae with few or no septae. The common environmental zygomycetes are very rapid growers on agar and can inhibit the growth of other molds on the plate, reducing the recovery of some of the molds in the sample; in culture analyses, the common types produce sporangia.