THE DISCOMYCETES OF EASTERN IOWA. 



243 



cation based upon structural characters is that by which this 

 may best be done. 



The classification used here with few exceptions is that pre- 

 sented by Schrceter and Lindau in Engler-Prantl, Natur- 

 lichen Pflanzen Familieu. The complete key to the genera 

 of the two orders Helvellinece and Pczizinece is given here as 

 presented in that work. 



Since the determinations have been made for the most part 

 without material for comparison, any corrections by those 

 interested will be gratefully received. 



KEY TO THE GENERA 



A — Hymenium exposed from the first 

 A — Hymenium at first closed. 



b — Hymenium open at an early stage, without 



firm covering ..... 



b — Hymenium inclosed in firm covering, opening 

 at maturity. 



c — Opening with a star-like aperture 

 c — Elongate opening with a slit-like aperture 



Helvellinece 



Pezizinece 



Phacidiinece 

 Hysteriinece 



heivveu-jne^: 



A — Receptacle borne on a stem. 



b — Pileus clavate or knob-like; asci non-oper- 

 culate ....... 



b — Pileus capitate or pileate ; asci operculate 

 A — Receptacle sessile ..... 



Geoglossacecp 



Helvellacea 



Rhizinacecp 



Geoglossace;^ 



A — Receptacle sessile on the stem or adnate with it. 

 b — Receptacle clavate, sessile on the stem, 

 c — Spores colorless, 1 -celled. 



d — Pileus sharply distinguished from the 



stem, bright colored . . . Mitrula 



d — Pileus not sharply distinguished, bright 



or dark colored .... Microglossum 



c — Spores several-celled. 



d — Spores colorless .... Leptoglossum 



d — Spores brown .... Geoglossum 



