ADVERTISEMENTS:
In this article we will discuss about the general characteristics and classification of discomycetes.
General Characteristics of Discomycetes:
Popularly the members of this group are called the cup fungi. The most distinctive feature is the cup or saucer-shaped usually fleshy ascocarp which is botanically known as the apothecium. The apothecia vary in colour through a wide range and may be red, yellow, orange, brown, black or even colourless.
They vary in shape as well. Often they are typical cups or discs, but other forms such as sponges, saddles, tongues, and bells are not in any way uncommon. The ascocarps invariably are open. The asci are club shaped or cylindrical in form and are arranged in columnar disposition (a palisade-like layer) on the surface or in open cavities.
ADVERTISEMENTS:
The only exceptions are the truffles in which the underground ascocarps remain closed. Paraphyses usually occur intermingled with the asci. In habit the Discomycetes are mostly saprobes found growing in high humidity of soil, humus, dead logs of wood and dung.
black or even colourless. They vary in shape as well. Often they are typical cups or discs, but other forms such as sponges, saddles, tongues, and bells are not in any way uncommon. The ascocarps invariably are open. The asci are club- shaped or cylindrical in form and are arranged in columnar disposition (a palisade-like layer) on the surface or in open cavities.
The only exceptions are the truffles in which the underground ascocarps remain closed. Paraphyses usually occur intermingled with the asci. In habit the Discomycetes are mostly saprobes found growing in high humidity on soil, humus, dead logs of wood and dung.
ADVERTISEMENTS:
The conidial stage appears to be non-existent in most cases. Gradual and progressive reduction in sexuality is another feature of this sub-series. It is accomplished by stages. In some genera such as Pyronema (Fig. 12.6) both the sex organs are functional.
Fusion between them takes place. The intervening walls at the point of contact dissolve. The protoplasts of the two sex organs unite. The male and the female nuclei arrange themselves in pairs (dicaryons). Same is the case with Lachnea stercorea.
Both the sex organs are fully developed. The antheridia are thus functionless. In Lachnea cretea the antheridium is totally absent. Humaria granulata goes a step further. The antheridia are absent.
This is accompanied by the disappearance of the trichogyne from the ascogonium (Fig. 12.15 A). Finally in Morchella, Humaria rutilans and Peziza vesicolusa both the sex organs are totally absent. The whole sexual apparatus is lacking. The sexual process simply consists in the union of two vegetative nuclei in a pair.
ADVERTISEMENTS:
Classification of Discomycetes:
In most of the Discomycetes the ascocarps are above ground. They are called epigean.
The epigean discomycetes are usually divided into the following two groups:
ADVERTISEMENTS:
1. Inoperculate Discomycetes:
The ascospores escape through an apical circular pore at the tip of the ascus or by splitting of ascus at the apex. This group includes two orders, namely, Ostropales and Helotiales.
2. Operculate Discomycetes:
The ascospores are released through a preformed apical pore which opens by a lid-like structure at the apex. The lid which is also called the operculum is hinged at the top of the ascus. The operculate Discomycetes comprise a single order Pezizales which is discussed here in some detail.
