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CLASS ASCOMYCETEAE: THE "PYRENOMYCETES" 



WITH the exception of the Order Laboulbeniales the Ascomyceteae so 

 far considered have been those whose spore fruits are apothecia or 

 possible modifications of apothecia. In this chapter are discussed those 

 orders which produce true perithecia with ostioles, or stromata containing 

 cavities within which the asci are developed. Because the life histories of 

 all but a few of these thousands of species are entirely unknown the rela- 

 tionships of these orders to one another and of the genera within the 

 orders are admittedly very uncertain. Indeed, with further study it is 

 almost certain that the limits of the orders will have to undergo radical 

 revision. For this reason a rather conservative attitude is taken as to 

 these groups. The author does not believe that the true relationships are 

 shown by the arrangement chosen but this is due to the ignorance of the 

 ontogeny of the species. 



Whether the perithecial forms should be treated after or before the 

 apothecial forms is a matter of convenience rather than of expression of 

 phylogenetic history. It seems likely that very early in the development 

 of the Ascomyceteae three tendencies began to be emphasized. In the one 

 the female sexual branch bore an oogone surrounded with a protective 

 layer, as in many Florideae; this group led to the Laboulbeniales. In the 

 two other series the female sexual organs were at first naked. In one of 

 these the number of ascogenous hyphae and their branches was great and 

 a rather wide-spreading spore fruit developed; the apothecial series of 

 fungi. In the third the ascogenous hyphae were shorter and usually few, 

 little branching if at all, and the protective structure formed about them 

 (the perithecium) remained relatively small and was arched over them 

 and closed or with only a comparatively small opening, the ostiole. So 

 far we have followed the first two series of development, we now return 

 to the relatively primitive forms again and start to follow the third series. 

 Because the spore fruits of this series were more often hard-walled and 

 small and like the stones of some small fruits the name " Pyrenomycetes " 

 was applied to include fungi of this nature (from the Greek pyren, the 



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