PHYLOGENY AND RELATIONSHIPS IN THE 



ASCOMYCETES 



i 



GEO. F. ATKINSON 

 Cornell University 



Pabt I. Aegument 



Perhaps there is no other large group of plants whose origin 

 and phylogeny have given rise to such diametrically opposed 

 hypotheses as the fungi. The presence of chlorophyll and the 

 synthesis of carbohydrates from inorganic materials are such 

 general and dominant characteristics of plants, that many 

 students regard them as the fundamental traits which pri- 

 marily marked the divergence of plant from animal life. Ac- 

 cording to this hypothesis all plants possess chlorophyll or 

 were derived from chlorophyll-bearing ancestors. 



No one questions the origin of the chlorophylless seed plants 

 from chlorophyll bearing ones by the loss of chlorophyll and 

 reduction of photosynthetic organs. 2 "What is more natural 

 then, than the hypothesis that the fungi have been derived 

 from chlorophyll-bearing ancestors? It is not my purpose 

 to discuss the question as to whether or not the Phy corny cetes, 

 or lower fungi, had an independent origin, or were derived 

 from one or several different groups of the green algae. I 

 wish to consider some of the evidence which points to the 

 origin of the Ascomycetes from fungus ancestry, rather than 

 from the red algae. 



1 The first part of this paper is the ahstract or argument as read at the anni- 

 versary proceedings. Because of the brief character of the abstract which renders 

 many of the statements more or less categorical, while some therefore will appear 

 dogmatic, the subject is further elaborated, and illumined by 

 of Notes which follow as an appendix in Part II. 



examples in a series 



* The chlorophylless seed plants constitute comparatively small, isolated 

 groups of separate origin from different families or orders of the spermatophytes. 

 They do not constitute a phylum. The situation is quite different with the 

 Ascomycetes, which make up a great phylum with ascending and diverging lines, 

 as well as descending branches. They do not give evidence of many isolated 

 groups derived by degeneration from many separate families of the red algae. 



Ann. Mo. Bot. Gard., Vol. 2, 1915 



(315) 



