It is the largest group of fungi, including over 60,000 species, 50% or so occurring in lichens and some, such as morels, are mycorrhizal. Most are terrestrial, though some are marine or fresh water. The group shows diversity from unicellular yeasts to large cup fungi and morels. They produce haploid sexual spores called ascospores by meiosis inside their characteristic sac like structures called asci (sing. Ascus). Meiosis follows nuclear fusion inside the ascus, commonly 8 ascospores are produced inside each ascus. Most sac – fruiting bodies called ascocarps-the visible morels etc. their hyphae are septate. They have lengthy dikaryotic phase that forms ascocarps. They reproduce asexually by conidia that are often dispersed by wind.