fungi

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A plural of fungus.

Century Dictionary and Cyclopedia

1. n. One of the lowest of the great groups of cellular cryptogams. The Fungi are chiefly distinguished by the absence of chlorophyl, and therefore by the lack of power to assimilate inorganic substances, being thus dependent for their food upon living or dead organic matter obtained from other plants or from animals. Consequently, also, they do not inhale carbonic acid and give off oxygen as chlorophyllous plants do in assimilation, but do inhale oxygen and give off carbonic acid as other plants do in respiration. The vegetative system consists of filiform cells, called hyphæ and the hyphæ of a fungus taken collectively are called the mycelium. The hyphæ are usually septate and branched; in some fungi, as Peronosporeæ and their allies, there are no septa except those which divide off the propagative cells or organs. Exceptions to the hyphal plan of structure occur in several cases. In the yeast-fungi and yeast-like stages of certain other fungi the plant consists of a succession of ellipsoid cells formed by budding; in the Chytridieæ certain species have no mycelium, but consist of a spherical or ovoid cell; in the bacteria the prevailing form is that of very minute spheres or rods, which multiply by fission; in. the vegetative stage of the Myxomycetes there is only a mass of protoplasm. The mycelium is said to be filamentous when the hyphæ are separate, or at most but loosely interwoven, as in the common molds; membranous when the hyphæ are so interwoven as to form a layer; fibrous when the hyphæ form branching strands, the latter being often of considerable size and indurated. In some groups. as the mushrooms, the interwoven hyphæ form a compound fungus-body of definite and regular shape. Fungi are saprophytic or parasitic, according as that from which they obtain their food is a dead organic substance or a living organism. Some parasitic species are facultative saprophytes, and some saprophytic species are facultative parasites. Among the saprophytic fungi are the common domestic molds and mildews, the “dry-rot” fungi, the greater number of ascomycetous and basidiomycetons fungi, which grow on dead wood, leaves, etc., or organic matter in the soil, also many Hyphomycetes, and the Myxomycetes. Among the parasitic fungi are the Uredineæ or rusts and Ustilagineæ or smuts, which grow upon wild and cultivated plants, also most Peronosporeæ, as represented by the potato-rot and American grape-vine mildew. Among the Ascomycetes, the Erysipheæ (powdery mildews) are all parasitic, as are also many other Pyrenomycetes and a few Discomycetes. Many parasitic species, especially the rusts, smuts, and mildews, cause great destruction to cultivated crops. The lichens are now considered by many botanists to consist of fungi parasitic upon algæ (the gonidia). (See lichen.) A few fungi grow upon living animals and man. Several species of Aspergillus cause a disease (otomycosis) of the human ear. Other fungi produce the skin-diseases favus and ringworm. Bacteria are believed to cause most or all of the fevers and contagious diseases of man and the lower animals. Species of Saprolegnia cause epidemics among fishes, especially the salmon. The principal parasites upon insects belong to the Entomophthoreæ and the genus Cordyceps. (See cut under Cordyceps.) Silkworms are attacked by a species of Botrytis, and bacteria cause epidemics among silkworms and other insects. Both sexual and asexual reproduction occur in fungi; the latter is present in all, and in many is the only kind that has been observed. The asexual spores (conidia) are most frequently produced upon the tips of uninclosed hyphæ, as in Hyphomycetes, or on short hyphæ produced in conceptacles, but sometimes by free cell-formation, as in Mucor. The sexual organs are of three types. In the conjugating fungi, Mucor and its allies, reproduction takes place by the union of two similar cells to form a zygospore. In Peronospora and its allies oogonia and antheridia are formed; the antheridium comes in direct contact with the oogonium, and a transfer of the protoplasm into the oosphere takes place. In the Ascomycetes, so far as known, a carpogonium takes the place of the oogonium, and the product of fertilization is usually a perithecium or apothecium containing asci and spores. (See Eurotium.) Modern classifications of fungi are of two kinds. That proposed by F. Cohn in 1872 classes together in primary groups fungi and algæ having similar modes of reproduction, employing the peculiar fungal characters in distinguishing the secondary groups; but the usual method recognizes fungi as wholly distinct from algæ, separated by physiological and morphological characters, in this respect agreeing with the old method. The artificial system formerly in use and still retained in some English books divides the fungi into the orders Ascomycetes, Physomycetes, Hyphomycetes, Coniomycetes, Gasteromycetes, and Hymenomycetes. De Bary in 1861 made four divisions: Phycomycetes, Hypodermiæ, Basidiomycetes, and Ascomycetes. Goebel (1882) does not include Myxomycetes and Schizomycetes with Fungi proper; the latter he divides into Chytridiaceæ. Ustilagineæ, Phycomycetes, Ascomycetes, Uredineæ, and Basidiomycetes. The Fungi Imperfecti of modern authors include a large number of forms, of which some are known, and most are suspected, to be the asexual stages of Ascomycetes. The principal groups of Fungi Imperfecti are the Sphæropsideæ; Melanconieæ, and Hyphomycetes. The number of known species of fungi is estimated at about 30,000, Most of the edible fungi are found among the mushrooms and pufiballs; but the truffle and morel are ascomycetous. Most of the species recognized as poisonous are mushrooms; but the ergot-fungus is ascomycetous. Some smuts are poisonous to cattle. Some fungi produce poisonous substances, as alcohol, by fermentation. Also called Fungales. See cuts under ascus, basidium, Clavaria, ergot, exoperidium, Fusicladium, and Puccinia.
2. Recent investigations have added much to the knowledge of the life-histories and relationships of this large group of plants. The term, as commonly used to include the slime-molds and bacteria as well as the fungi proper, does not signify a natural group. The present tendency is to restrict its use to the Eumycetes (true fungi). The cytological studies of Harper and others confirm the opinion that the rusts (Uredinales) are most closely related to the Basidiomycetes, while the researches of Thaxter have shown the existence of what appears to be a new order, the Myxobacteriales, showing characters of both Myxomycetes and bacteria. Various recent systematic arrangements of the fungi have been proposed, notably those of Brefeld, Schröter, Saccardo, and Bugler and Prantl. These classifications differ chiefly in the terminology used, the relative rank given to different groups, and the position assigned to certain orders of more or less doubtful relationship. The sporological system of Saccardo, used in his “Sylloge Fungorum” as a basis for the division of the larger groups of the Pyrenomycetes, Discomycetes, and Fungi Imperfecti, is very convenient but artificial. The following arrangement is based upon that given in Engler's “Syllabus.” The termination of the ordinal names is that at present adopted and has been used by Underwood. The lichens have been added to the classes of fungi to which they belong. Class I. Myxomycetes: orders Acrasiales, Plasmodiophorales, Myxogastrales, Myxobacteriales. Class II. Schizomycetes: orders Eubacteriales, Thiobacteriales. Eumycetes (true fungi): Class III. Archimycetes: order Chytridiales. Class IV. Zygomycetes: orders Mucorales. Entomophthorales. Class V. Oömycetes: orders Saprolegniales, Peronosporales. Class VI. Ascomycetes: orders Protonnycetales, Saccharomycetales, Exoascales, Aspergillales, Perisporiales, Hypacreales, Dothideales, Sphæriales. Laboulbeniales, Tuberales, Hysteriales, Phacdiales, Pezizales, Helvellales. Subclass Ascolichenes: orders Parmeliales, Lecideales, Graphidales, Caliciales, Verrucariales. Fungi Imperfecti: orders Sphæropsidales, Melanconiales, Moniliales. Class VII. Basidiomycetes: subclass Hemibasidii — order Ustilayinales; subclass Protobasidii — orders Uredinales, Auriculariales, Tremellales, Dacryomycetales, Exobasidiales, Agaricales, Phallales, Hymenogastrales, Lycoperdales, Nidulariales, Sclerodermatales. Subclass Hymenolichenes.

Wiktionary

1. n. Plural form of fungus.

GNU Webster's 1913

1. n. (Biol.) A group of thallophytic plant-like organisms of low organization, destitute of chlorophyll, in which reproduction is mainly accomplished by means of asexual spores, which are produced in a great variety of ways, though sexual reproduction is known to occur in certain Phycomycetes, or so-called algal fungi. They include the molds, mildews, rusts, smuts, mushrooms, toadstools, puff balls, and the allies of each. In the two-kingdom classification system they were classed with the plants, but in the modern five-kingdom classification, they are not classed as plants, but are classed in their own separate kingdom fungi, which includes the phyla Zygomycota (including simple fungi such as bread molds), Ascomycota (including the yeasts), Basidiomycota (including the mushrooms, smuts, and rusts), and Deuteromycota (the fungi imperfecti). Some of the forms, such as the yeasts, appear as single-celled microorganisms, but all of the fungi are are eukaryotic, thus distinguishing them from the prokaryotic microorganisms of the kingdon Monera.

WordNet 3.0

1. n. the taxonomic kingdom including yeast, molds, smuts, mushrooms, and toadstools; distinct from the green plants