410 Illinois State Laboratory of Natural History. 



U. salicis, (DC.) Winter. 

 (Die Pilze, II., p. 40.) 



Erysiphe salicis, DC. (Flore Franc., JL, p. 273). 



Erysiphe p&puli, DC. (Flore Franc., VI., p. 104). 



Alphitomorpha adunca, guttata, Wallr. (Verb. Naturf. Freunde, L, pp. 



37, 42). 



Erysibe adunca, obtusata, Lk. (Spec. Plant., VI., 1, p. 117). 

 Erysiphe adunca, Grev. (Scott. Crypt. Flora, V., tab. 296). 

 Uncinula adunca, Le"v. (Ann. Sci. Nat., Ser. III., Tome XV). 

 Undnula leucuknta, Howe (Trans. Albany Inst, VII., quoted in 



Amer. Nat., VII., p. 58). 

 Uncinula heliciformis, Howe (Torr. Bull., V., p. 4). 



Amphigenous. Mycelium abundant, persistent; perithecia 

 usually large, 100-160 ^, wall-tissue soft, elastic, reticulations 

 rather small and indistinct; appendages variable in number, 

 usually very numerous, hyaline, not much swollen at the tip, 

 once to twice as long as the diameter of the perithecium; asci 

 from 4 or 5 to 12 or more, ovate; spores usually 4 or 5, some- 

 times 6-8. 



OIL Salix aps.: La Salle, Sept. 20, 1602; Henry, Sept. 28, 

 1721; Jo Daviess, Sept. 20, 6029, 6030, 6031; Stephenson, Sept. 

 21, 6083. Salix petiolaris: Piatt, Aug. 17, 1143. Salix car- 

 data: McHenry, Aug. 20, 1152, Aug. 24,1255, 1256; Cook, Sept. 

 5, 1435;. Jo Daviess, Sept. 18, 5974. Populus tremuloides: 

 McHenry, Aug. 23, 1250, Aug. 31, 1397; Jo Daviess, Sept. 

 18, 6018. Populus grandidentata : La Salle, Sept. 17, 1579. 

 Populus heterophylla: Union, Oct. 25, 2020, 2031; Oct. 31, 

 2142. 



This species is quite variable, as are most of the abundant 

 and widely distributed ones belonging to the family. It is 

 usually known as U. adunca, Lev.; but De Candolle's name has 

 priority, and is adopted by Winter (Die Pilze, II., p. 40) and 

 Tulasne (Fung. Carp. I., p. 198). The asci are usually described 

 with only four or five spores, but our specimens frequently show 

 as many as six, and sometimes seven or eight. 



U. leuculenta, Howe, is described as occurring on Populus, 

 with fewer and longer appendages and five or six spores. Illi- 

 nois specimens on Populus sometimes show rather longer ap- 

 pendages than on Salix, but as the more numerous spores are 

 frequent on both hosts, there is no sufficient ground for sepa- 



