are characterised primarily by the sexual spores
) being produced on a cell called a basidium
, usually in fours. Many but not all have septal
structures called a clamp connection
during most of the life cycle. No other group of fungi has these.
There are about 25,000 species in this division including the more familiar types of fungi whose fruiting bodies are popularly known as mushrooms and toadstools. A number of these are edible but also are included many which are toxic
or hallucinogenic. This group also contains those that decay wood or attack living trees, others, which rot down forest litter. Plus the class of fungi known as rusts and smuts.
Basidiomycete have many features in common with the Ascomycetes
cell walls that are regularly septate
, cell division often accomplished by clamp formation, and the presence of an extended dikaryon
stage. This means that the two nuclei
brought together in mating do not fuse in the thallus
of the fungus, but instead exist side-by-side in each cell.
is the cell in which karyogamy
(nuclear fusion) and meiosis
occur, and on which haploid
basidiospores are formed. The basidium produce four basidiospores, borne on the tips of little prongs which project from the apex, and which are called sterigmata
are produced if an asexual
stage is present.
Millions of these are packed together in the hyrneniurn,
which covers the exposed or enclosed surfaces of the sporocarp
, which are quite variable in form. These are then discharged a short distance into the space between the gills, tubes, or teeth, of the fungi, subsequently falling the short distance out of the cap, to be carried away on air currents.
Basidiomycetes are divided into four classes depending on the form of their basidium. The Teliomycetes and Urediniomycetes are presently not covered here, as they do not produce a basidiocarp
In this class the fruiting surface, or hymenium is external
(Homobasidiomycete Fungi)(Substantial mushrooms)
This subclass has exposed spore surface such as pores or gills, from which each basidiospore in turn is actively shot away. The class contains those fungi that are coincided to be 'mushrooms', which have a stalk, and a fleshy cap. The other members are those referred to as 'shelf fungi', which lack a stalk, and grow directly from wood.