94 Forest Club Annual 



occupied, which eventually turns dark brown or black because 

 of the many pycnidia present. Sometimes the pycnidia are 

 formed in definite colonies. The spores are oblong, hyaline, 

 4-1 microns, continuous, borne on densely fasciculate basidia 

 10-12 microns long. The pycnidia often break open by an 

 irregular cleft, and then the 1 membranous walls become folded 

 back as shown in fig. 2L On living leaves of Glcditsia triacan- 

 thos. During the season of 1910 the Honey Locust was very 

 badly infected with this fungus, (see fig. 20.) the leaflets often 

 being completely covered by the densely aggregated black 

 pycnidia. 



Piggotia 



Pycnidia flattened, thin, membranous sub-cuticular, opening 

 not by a regular ostiole, but variously perforate, not cleft as in 

 Lcptostroma. Spores oblong or cylindrical, continuous, hyaline. 

 Basidia cylindric. 



Piggottia fraxini B. & C. 



Pycnidia occuring in clusters, forming black granular spots 

 scattered in the lower surface of the leaf, breaking through the 

 cuticle in roughened groups. Spores oblong, very small, 5-7 

 microns long. Very common on the fallen leaves of Fraxinus 

 lanccolata. 



Discosia 



Pycnidia broadened to disciform, almost superficial, easily 

 separating, dark, often black, with or without an ostiole, mem- 

 branous. Spores oblong, somewhat curved, 2-many septate, 

 often 3-septate, 1-ciliate, hyaline or dilutely colored, borne upon 

 rod-like basidia. 



Discosia artroccras (Tode) Fr. 



Pycnidia clustered, orbicular, black, shining, at first convex, 

 at length depressed near the dot-like ostiole, finally collapsing 

 then wrinkled or folded. Spores sausage-shaped, provided at 

 each end x with a bristle or cilium, 3-septate, hyaline or yellowish, 

 18-4 microns, bristles 10-15 microns long. Quite common on 

 Platanus occidentalis and Quercus sp. 



Melanconiales 



In this order of imperfect fungi, well developed, typical 

 pycnidia are lacking, or they are typically reduced to a stratum 

 merely. These strata are sub-cuticular, typically bearing basidia 

 of various sorts upon which the spores are formed, constituting 

 masses or acervuli which are immersed or erumpent, black, gray, 





