A fungus is a non-chlorophyllous plant whose vegetative body (thallus) consist of threadlike filaments (hyphae) aggregated into branched systems (mycelia). Fungi reproduce by sexual and/or asexual means and have membrane-bound nucleus in each cell. Their cells have cell walls.
Etymology. 1527, from L. fungus, learned alternative to mushroom. (Though funge was used in this sense late 14c.). The L. is believe to be cognate with (or derived from) Gk. sphongos, the Attic form of spongos "sponge".
Hyphae is a term originating from the Greek word for web. The word mycelium derives from the Greek word mykes, which refers to fungi. Fungi are of ancient lineage: their fossil record extends back to the Devonian and Pre-Cambrian eras. Ancient Romans held a spring festival each year (called Robigalia) based on the superstitious belief that offerings to the gods would help ward off the "rubigo", or rust diseases. Fungi reproduce principally by means of spores, which are formed asexually or as the result of a sexual process. Spores are very diverse in size, form, and longevity, and these characteristics are used partly as a basis of classification.
Fungi exist as primitive ("lower") forms and more evolutionarily advanced ("higher") forms. Some fungi produce spores in elaborate fruiting bodies (e.g., mushrooms). Like the bacteria, fungi are extremely prolific: A single kernel of wheat destroyed by a smut fungus contains from 2 million to 12 million spores. Fungus spores range in size from about 4 micrometers to more than 100 micrometers. ungus spores can be carried long distances wind (hundreds to thousands of miles), water, humans and insects. Most fungi are facultative saprophytes. A fungus may have two legitimate names: one for the asexual and one for the sexual stage. Some fungi produce up to 5 different spore types.
Theories of origin of primitive fungi:
- they are degenerative algae.
- the algae and the fungi evolved as two parallel series.
- fungi derived from protozoa.