Ascomycota

The Ascomycota is the largest phylum in the kingdom Fungi with about 99,000 species that are commonly called ascomycetes. Included in this phylum are simple yeasts, as well as molds (microfungi), cup fungi, morels, and lichens. The majority of lichens are ascomycete fungi with a symbiotic (mutualistic) alga within its body.

Sexual Reproduction in the Ascomycota

The sexual spore in this phylum is the ascospore produced within a sac-like structure called an ascus (pl. asci). Typically, there are 8 ascospores within each ascus. In many species the asci are formed within a fruiting body which is called an ascocarp or an ascoma. Some ascocarps are microscopic, while others are macroscopic and large. Morels and cup fungi are examples of macroscopic ascocarps. The depressions in the morels shown below are lined with asci containing the eight ascospores. In many ascomycetes, the ascospores are actively shot from the ascus into the atmosphere through mechanisms that require moisture and are found in the atmosphere following rain or during high humidity. Ascospores have a varied morphology from small unicellular structures to large multicellular structures. 

Asexual Reproduction in the Ascomycota

Asexual reproduction in the Ascomycota is generally by the formation of conidia (sing. conidium). Conidia are asexual spores that are not formed in a sporangium. Depending on the species, conidia are formed on regular hyphae or on specialized hyphae branches called conidiophores (conidium bearing structures). Many of these asexual ascomycete spores are the most abundant airborne spores in temperate climates, and many are dominant members of the dry air spora. Common asexual ascomycetes include the genera Cladosporium, Alternaria, Penicillium, Aspergillus, and many others.