98 Forest Club Annual 



are parasitic upon a wide range of hosts. These numerous spe- 

 cies are distinguished with difficulty, often intergrading in a most 

 puzzling manner. The host plant is about the only key to the 

 species, and often this criterion fails. Some of our common 

 species follow. 



Cercospora condcnsata E. & K. 



Fascicles of fertile hyphae on brown or dirty-white, round 

 spots with an obscure dark border. The hyphae are brown, 

 obtuse and somewhat roughened above, 30-80x4-5 microns, 

 densely compacted so as to form tiny, dark, tubercle-like fascic- 

 les resembling perithecia. Spores slender-clavate or cylindrical, 

 6-9 septate, 60-75x4 microns. On leaves of Gleditsia triacanthos. 



Cercospora glandulosa E. & K. 



Spots on the lower side of the leaf, becoming reddish-brown, 

 limited above by a slightly raised border. Hyphae cespitose as 

 in the above species, brown, stout, somewhat undulate above, 

 50-70x4-5 microns. Spores hyaline, slender, 3-5 septate, 70- 

 100x3 microns, gradually narrowed above. Common on leaves 

 of Ailanthus glandulosa. 



Cercospora gymnocladi E. & K. 



Spots mostly on the upper side of the leaf. Hyphae on 

 grayish-brown spots 3-4 mm. in diameter with a discolored bor- 

 der, in minute dot-like tufts, simple, continuous, brown, 18-2.5x4 

 microns. Spores obclavate-cylindrical, brown, 3-6 septate, 40- 

 50x5-6 microns, often much shorter, on Gymnocladus dioicus. 

 Other species : 



Cercospora circumscissa Sacc. On species of Primus. 

 Cercospora negundinis E. & E. On Acer ncgundo. 

 Cercospora rhamni Fuckel. On Rhamnus caroliniana. 



Ceratophorum 



Sterile hyphae few, creeping over the discolored spots ; 

 fertile hyphae very short or little different from the spores. 

 Spores fusoid to cylindrical, 2-many septate, sooty, upward 1-3 

 toothed, incurved, pale. 



Ceratophorum ulmicolum E. & K. 



Spots on both sides of the leaf, orbicular, dirty-brown with 

 a small white center. Spores fusoid, attenuated below into a 

 hyaline, obtuse base, and prolonged above into a curved, hyaline 

 beak, swollen, dark or olivaceous, 5-7 septate near the middle, 

 60-100x11-14 microns. On living leaves of Ulmus pubescens. 

 (To be continued) 



