ascusbearing

Ascusbearing, also written ascus-bearing, is a descriptive term used in mycology to refer to fungi that form asci, sac-like cells in which sexual spores, called ascospores, develop through meiosis and subsequent mitotic divisions. The presence of asci is a defining feature of the phylum Ascomycota, distinguishing ascus-bearing fungi from the basidiomycetes, whose reproductive cells are basidia.

Within ascus-bearing fungi, asci are produced in various fruiting structures, including apothecia, perithecia, and cleistothecia, or directly within yeast life cycles. Depending on group, asci can be unitunicate (one wall layer) or bitunicate (two wall layers), and can release spores through an operculate lid or by rupture. A typical ascus contains eight ascospores, though counts can vary by lineage.

Ecologically and economically important ascusbearing fungi include many familiar genera such as Saccharomyces (brewer’s and baker’s yeast), Aspergillus and Penicillium (molds important in food production and industry), and Morchella (morels). Lichen-forming fungi are often ascomycetes as well, contributing to symbiotic partnerships with photosynthetic partners.

In taxonomy, ascusbearing is a broad informal term for fungi in Ascomycota, which is subdivided into groups such as Saccharomycotina and Pezizomycotina. The term is commonly used in educational or descriptive contexts to emphasize a key reproductive characteristic.