Glossary of Terms

(more glossary terms will be added with future posts)



An annellide is very similar to a phialide. Both structures produce and extrude conidia. However, as an annelide extrudes conidia it grows. As each conidium is released, the annelide acquires a ring of new cell wall material. Phialides do not increase in length.


This is a sexual spore that is produced within the ascus.

Ascus (pl. asci)

This is a little sack that holds ascospores. The ascus or asci are formed inside the perithecium or cleistothecium and they usually dissolve when ascspores are released. Each ascus holds about 2-8 ascopsores.


In reference to the genus Aspergillus; a biseriate phialide is supported by a metula which forms on the vesicle. This differs from a uniseriate phialide, which forms directly on the vesicle.

Cleistothecium (pl. Cleistothecia)

Cleistothecia are large fruiting bodies, usually round, and are similar to perithecia. What differentiates cleistothecia from perithecia is the lack of an ostiole. The cleistothecium will hold asci and ascopsores until it ruptures, which then releases the inner contents.


The conidia form on this structure, which forms on the hyphae.

Conidium (pl. Conidia)

Asexual reproductive structure of fungi. Conidia can form directly on the hyphae or the conidiophore. Conidia are borne externally (as opposed to being enclosed within a sporangium). If a fungus produces 2 types of conidia, the smaller single celled conidia are called microconidia. The larger conidia may be segmented, and are referred to as macroconidia.

Dematiaceous Fungi

Fungi that are considered dematiaceous have structures that are pigmented brown or black.

Foot Cell

Where hyphae merges with the base of the conidiophore, giving the impression of a foot. Typically seen in Aspergillus species.

Hülle Cell

This is a sterile cell associated with cleistothecia produced by the sexual stage of some Aspergillus species. This cell is typically thick with a small lumen. It may be globose, irregular, or elongate in shape.

Hyaline Hyphomycete

A hyaline hyphomycete is a fungus that has colorless hyphae and produces conidia that may be colorless or brightly pigmented. This is basically the opposite of dematiaceous fungus, which have darkly pigmented hyphae and conidia.

Hypha (pl. Hyphae)

Long, branching tubular structures that compose most fungi. Many strands of hyphae matted together form the mycelium, or the colony surface of the fungus.

Metula (pl. Metulae)

Like a pedestal, the metula is a separate structural component of the conidiophore which supports the phialide. This can be seen in such genera as Aspergillus, Penicillium, and Paecilomyces.


This word describes conidia that have both transverse and longitudinal septations. Can be seen in Alternaria species, Ulocladium, Stemphylium, Pithomyces, and Epicoccum.


An opening or hole, as can be seen in perithecia.


This is a large fruiting body; typically round or pear shaped and holds asci and ascospores. The perithecium has an opening called an ostiole. This opening is what differentiates perithecia from cleistothecia.


This structure is typically shaped like a flask, vase, or bowling pin. It is a cell that produces and shoots out conidia. The phialide does not increase in length with each new conidium produce, as seen with the annelide.


In reference to the genus Aspergillus; the uniseriate phialide forms directly on the vesicle. This differs from the biseriate phialide which is supported by a metula.


Enlarged, rounded structure that forms at the end of a conidiophore. In Aspergillus species, it bears the phialides.