The fungi are of following kinds:
- Myxomycetes, the Slime moulds, which have irregular shape.
- Phycomycetes, are unicellular, filamentous and branched e.g. Rhizopus and Phytophthora.
- Ascomycetes, are one celled (e.g. yeasts) or multicellular branched e.g. Aspergillus, Penicillium, and Neurospora.
- Basidiomycetes, are multicellular, branched, and are represented by rusts, smuts, Mushrooms and toadstools, which are large enough to be seen by naked eyes.
- Deuteromycetes, are multicellular filamentous branched fungi which reproduce only by asexual means e.g. Alternaria.
- Lichens and mycorrhizae which exist in symbiotic associations.
Yeasts are fungi which do not produce any hyphae. These are generally in the form of single oval cells.
Yeast is saprotrophic. It can directly absorb simple sugar (glucose) but for obtaining sucrose (cane sugar) it gives out the enzyme invertase or sucrase which breaks down sucrose into simple sugars. The simple sugars are then simply absorbed into the cell.
Myxomycetes (Slime Moulds)
These consist of a naked, creeping multinucleate mass of protoplasm sometimes covering up to several square metres. The nuclei are diploid.
Basidiomycetes (Mushrooms and Toadstools)
The vegetative part of the mycelium lies embedded in the substratum (in ground or in wood). When conditions are favourable the umbrella like mushrooms grow out with a stalk and a cap.
These are a combination of a certain fungus and a green or blue green alga which live in a symbiotic (mutually beneficial) association. The green or blue green alga prepares food while the fungus gives protection, and absorbs water and minerals from the surroundings.