IOWA DISCOMYCETES 43 



that other students may take up the work where it is left and 

 carry it on to its completion. To say that there are five hundred 

 species of this group in Iowa would, to my mind, be only a 

 reasonable estimate. 



To the various individuals who have contributed to this work 

 acknowledgments are made in the proper place and need not be 

 repeated here. However in addition to the members of the 

 botanical department of the State University of Iowa, I wish to 

 express thanks to Professor L. H. Pammel of Iowa State College 

 for his kindness in loaning to me for study the discomycetes in 

 the Holway collection of that institution. 



For characteristics and life-history of the group the reader 

 will consult the Iowa Natural History Bulletin already cited. 



CLASSIFICATION 



The classification adopted in this paper is for the most part 

 that offered in Engler & Prantl, Natiirlichen Pflanzen Familien 

 with some variation and the introduction of several genera not 

 recognized in that work. Only such orders, families, and genera 

 are included in the key as are represented by species described 

 in this paper. 



KEY TO THE ORDERS. 



Hymenium exposed from the first. ... I. HELVELLINEJE. 



Hymenium at first closed. 



Hymenium open at an early stage, without firm 



covering II- PEZIZINKE. 



Hymenium enclosed in a firm covering, opening 

 at maturity. 

 Opening with a stellate or irregular aperture III. PHACTDIINEiE. 



Elongate, opening with a slit-like aperture. IV. HYSTERIINEJE. 

 KEY TO THE FAMILIES. 

 Helvellixe^;. 



Receptacle borne on a stem. 



Pileus elavate or knob-like; asci non-operculate 1. Geoglossaceae 



Pileus capitate or pileate; asci operculate. . 2. Helvellaceae 



Receptacle sessile 3. Rhizinaceae 



