Fungus commonly known as sac fungi or ascomycetes, constitute the largest taxonomic group within the Eumycota. These fungi form meiotic spores called ascospores, which are enclosed in a special sac-like structure called an ascus. This phylum includes morels, a few mushrooms and truffles, unicellular yeasts (e.g., of the genera "Saccharomyces", "Kluyveromyces", "Pichia", and "Candida"), and many filamentous fungi living as saprotrophs, parasites, and mutualistic symbionts (e.g. lichens). Prominent and important genera of filamentous ascomycetes include "Aspergillus", "Penicillium", "Fusarium", and "Claviceps". Many ascomycete species have only been observed undergoing asexual reproduction (called anamorphic species), but analysis of molecular data has often been
Tree fern tree fern), "Cystodium", "Leptopteris", "Lophosoria", "Sadleria", "Thyrsopteris" and "Todea" could also be considered tree ferns in a liberal interpretation of the term. Tree ferns are found growing in tropical and subtropical areas, including cool to temperate rainforests in Australia, New Zealand and neighbouring regions (e.g. Malaysia, Lord Howe Island, etc.). Like all ferns, tree ferns reproduce by means of spores formed on the undersides of the fronds. The fronds of tree ferns are usually very large and multiple-pinnate. Tree ferns do not form new woody tissue in their trunk as they grow. Rather, the trunk is supported by a fibrous