<P> The Ascomycota is characterized by a high degree of specialization; for instance, certain species of Laboulbeniales attack only one particular leg of one particular insect species . Many Ascomycota engage in symbiotic relationships such as in lichens--symbiotic associations with green algae or cyanobacteria--in which the fungal symbiont directly obtains products of photosynthesis . In common with many basidiomycetes and Glomeromycota, some ascomycetes form symbioses with plants by colonizing the roots to form mycorrhizal associations . The Ascomycota also represents several carnivorous fungi, which have developed hyphal traps to capture small protists such as amoebae, as well as roundworms (Nematoda), rotifers, tardigrades, and small arthropods such as springtails (Collembola). </P> <P> The Ascomycota are represented in all land ecosystems worldwide, occurring on all continents including Antarctica . Spores and hyphal fragments are dispersed through the atmosphere and freshwater environments, as well as ocean beaches and tidal zones . The distribution of species is variable; while some are found on all continents, others, as for example the white truffle Tuber magnatum, only occur in isolated locations in Italy and Eastern Europe . The distribution of plant - parasitic species is often restricted by host distributions; for example, Cyttaria is only found on Nothofagus (Southern Beech) in the Southern Hemisphere . </P> <P> Asexual reproduction is the dominant form of propagation in the Ascomycota, and is responsible for the rapid spread of these fungi into new areas . It occurs through vegetative reproductive spores, the conidia . The conidiospores commonly contain one nucleus and are products of mitotic cell divisions and thus are sometimes called mitospores, which are genetically identical to the mycelium from which they originate . They are typically formed at the ends of specialized hyphae, the conidiophores . Depending on the species they may be dispersed by wind or water, or by animals . </P> <P> Different types of asexual spores can be identified by colour, shape, and how they are released as individual spores . Spore types can be used as taxonomic characters in the classification within the Ascomycota . The most frequent types are the single - celled spores, which are designated amerospores . If the spore is divided into two by a cross-wall (septum), it is called a didymospore . </P>

The asexual spores produced by members of the phylum ascomycota are called