|Basidiomycetes (The Club Fungi)|
|Basidiomycetes are characterised primarily by the sexual spores (basidiospores) 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
|Basidium and spores taken through a microscope X 600|
| Basidiomycete have many features in common with the Ascomycetes; mycelia with chitinous 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. |
Basidium 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. Conidia 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. See the life cycle drawing or try some of the links below for a better understanding.
|Formation of a clamp|
connection on hypha
of a basidiomycete
A view through a microscope showing the clamp connection on indervidual hypha.
|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.|
|Class: Hymenomycetes |
In this class the fruiting surface, or hymenium is external
Order: AgaricalesFamily: Agaricaceae
Order: CantharellalesFamily: Cantharellaceae
Family: DacrymyceaceaeFamily: Gomphaceae
|Class: Teliomycetes and Urediniomycetes (Rust and Smuts)|
In these two orders, not presented here, a basidiocarp is not formed, karyogamy occurs in a thick-walled resting spore (teliospore), and meiosis occurs upon germination of teliospore. These orders are sometimes put in a separate class, the Teliomycetes.
Uredinales are highly specialised parasites of higher plants with life cycles typically having up to five spore stages and two alternating hosts. The rusts cause many serious diseases of economically important hosts, including trees. They also have perhaps the most complex and perplexing life cycles, and variations on those cycles, of any group of organisms.
|Basidiomycetes Club Fungi|
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