Fungi are a mixed group of living things, linked by features of their cells. Most fungi are multicelled, and many of their cells contain more than one nucleus.
Fungi are found in most environments, but are particularly important in places like forest floors, where they consume litter and many microarthropods eat them.
Most fungi reproduce by spores, though some fungi reproduce by growing extensions of their hyphae into new areas, once a spore has established a new growth.
Fungi play an essential role by breaking down and recycling dead material, so that the nutrients contained in the dead material can be used again.
Because they live in highly competitive environments, many fungi produce antibiotics and other poisons that are able to harm predators or bacteria.
Fungi have caused poisoning by ergotism in the past, when the ergot fungus has attacked a rye crop. Other fungi can make nut crops poisonous.
Fungi cause a number of unpleasant or dangerous diseases in humans like tinea (athlete's foot), thrush, aspergillosis, histoplasmosis, ergotism and ringworm.
The Basidiomycetes (mushrooms, toadstools and similar forms) make a natural grouping within the Fungi, linked by a number of characteristics.
Yeasts can be observed in the process of respiration, and may be shown to use a remarkably similar set of genes and biochemicals found in other organisms.
A fungus can sometimes be found associated with one of the algae in a lichen: this is often regarded as a symbiosis, but is more like helotism.
Fungi form mycorrhiza on many plants, symbiotic threads that grow out from the roots, and play the same role as root hairs, taking up water and minerals.