ioo DISCOMYCETES [ch. 



Hymenium incompletely exposed at maturity 



ascophore round, aperture usually stellate Phacidiales. 



ascophore elongated, opening by a slit HYSTERIALES. 



Hymenium enclosed at maturity Tuberales. 



Pezizales 



The Pezizales are characterized by the fleshy or sometimes leathery 

 ascocarp, bounded, except in the Pyronemaceae, by a more or less definite 

 peridium which is closed at first and opens later, giving the mature fruit a 

 cup or saucer shape. 



This dehiscence is due to the growth of a conical mass of paraphyses 

 which push out at the apex of the ascocarp. Fresh paraphyses and, a little 

 later, asci grow up amongst those first formed and the peridium is pushed 

 wide open and the hymenium exposed. 



The asci contain usually eight, but sometimes four, sixteen, thirty-two, 

 or numerous spores, which germinate typically by means of germ-tubes, but 

 which, in a few cases, give rise by budding to conidia. Various accessory 

 spores, including conidia, chlamydospores and oidia, are also produced. 



The mycelium is well developed and filamentous, rarely forming a scle- 

 rotium. The species are parasitic or saprophytic on the ground or on dead 

 parts of plants ; in many cases they are coprophilous. 



Considering the very large size of the group the number of species 

 investigated is small. In a few of these, normally functional male and 

 female organs have been found, in some the antheridium has disappeared, 

 and in many the oogonium is also lacking. Where an oogonium is present 

 it gives rise to the ascogenous hyphae, while the paraphyses originate from 

 the stalk or from the surrounding cells (fig. 52). 



The group may be divided into the following families : 



Peridium continuous with hypothecium 



Peridium incomplete; ascocarps usually compound PYRONEMACEAE. 



Peridium well-developed 



asci not rising above the surface when ripe ; asco- 



spores usually uniseriate PEZIZACEAE. 



asci rising above the surface when ripe ; ascospores 



often coloured and biseriate Ascobolaceae. 



Peridium distinct from hypothecium 



Peridium of elongated hyphae (pseudoprosenchymatous) HELOTIACEAE. 

 Peridium pseudoparenchymatous MOLLISIACEAE. 



Peridium absent or ill-defined ; epithecium formed CelidiaCEAE. 



Peridium tough ; epithecium formed 



ascocarp free Patellariaci \i 



ascocarp embedded when young CENANGIACEAE. 



Apothecia numerous, sunk in a stroma Cyttariaceae. 



