The subdivision Zygomycotina has a single class, Zygomycetes. This class includes fungi (bread molds or pin molds) that typically produce an abundant and rapidly growing aerial, coenocytic mycelium and are common causes for the decay of foods and other rich sources of organic material. The cell walls contain chitin as a primary component. The cells walls reproduce asexually by means of nonmotive spores (sporangiosphores) of the mycelium. In some species, such as Rhizopus Nigricans, the sporangia arise in clusters with rhizoids at the base and hyphal strands (stolons) interconnecting the clusters. The spores are released by breakdown of the sporangial wall and dispersed by air or water currents.
Sexual reproduction may occur between different parts of the same mycelium or between two self sterile but cross fertile strains of opposite mating type. The letter is regulated by a single pair of genes, or alleles. One gene is said to be of the plus mating type and the other of the minus mating type. The gametangia, or sex organs, fuse to form a dormant, thick walled, pigmented, and often sculptures eventually germinate to produce a new haploid mycelium.
Other Subdivisions:
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