Dikarya (inc. Deuteromycota)
A fungus (pronounced /ˈfʌŋɡəs/) is a eukaryotic organism that is a member of the kingdom Fungi (pronounced /ˈfʌndʒaɪ/ or /ˈfʌŋɡaɪ/). The fungi are a monophyletic group, also called the Eumycota (true fungi or Eumycetes), that is phylogenetically distinct from the structurally similar slime molds (myxomycetes) and water molds (oomycetes). Fungi are heterotrophic organisms that possess a chitinous cell wall, and most species grow as multicellular filaments called hyphae that form a mycelium; some species grow as single cells. Fungi reproduce sexually or asexually via spores, which are often produced on specialized structures or in fruiting bodies. Some fungi have lost the ability to form reproductive structures, and propagate solely by vegetative growth. Commonly known fungi include yeasts, molds, and mushrooms, which are general descriptions based on appearance and growth form that are often applied to groups of unrelated species. The discipline of biology devoted to the study of fungi is known as mycology, which is often regarded as a branch of botany, but fungi are genetically more closely related to animals than to plants.
Abundant worldwide, most fungi are invisible to the naked eye because of the very small size of their vegetative structures. They live mainly in soil, on dead matter, and as symbionts of plants, animals, or other fungi. They perform an essential role in decomposing organic matter in ecosystems and have fundamental roles in nutrient cycling and exchange. Fungi may become noticeable when fruiting, either as mushrooms or molds. They have long been used as a direct source of food, such as mushrooms and truffles, as a leavening agent for bread, and in fermentation of various food products, such as wine, beer, and soy sauce. More recently, fungi have been used as sources for various enzymes important in industry and used in detergents, and, since the 1940s, for the production of antibiotics. Fungi are used as biological agents to control weeds and pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides that are toxic to animals including humans. The fruiting structures of a few species are consumed recreationally or in traditional ceremonies as a source of psychotropic compounds. Fungi can break down manufactured materials and buildings, and become significant pathogens of humans and other animals. Losses due to fungal diseases of crops (e.g., rice blast disease) or food spoilage can have a large impact on human food supplies and local economies.
The fungus kingdom encompasses an enormous diversity of taxa with varied ecologies and life cycle strategies, and morphologies ranging from amoeba-like protists and single-celled aquatic chytrids to large mushrooms. However, little is known of the true biodiversity of Kingdom Fungi, which has been estimated at around 1.5 million species, with about 5% of these having been formally classified. Ever since the pioneering 18th and 19th century taxonomical works of Carl Linnaeus, Christian Hendrik Persoon, and Elias Magnus Fries, fungi have been classified according to their morphology (e.g., characteristics such as spore color or microscopic features) or physiology. Advances in molecular genetics have opened the way for DNA analysis to be incorporated into taxonomy, which has sometimes challenged the historical groupings based on morphology and other traits. Phylogenetic studies published in the last decade have helped reshape the classification of Kingdom Fungi, which is divided into one subkingdom, seven phyla, and ten subphyla.