Parasitic Fungi of Illinois. 421 



the tips, even in the most mature specimens, are not at all re- 

 curved. This is clearly different from the regular and compact 

 branching and recurved tips of the appendages on Lathy rus, 

 which, as Trelease himself observes, " closely resemble those of 

 M. Ravenelii, B." 



M. alni, (DC.) Winter. 

 (Die Pilze, TI., p. 38.) 



Erysiphe alni, betulse, DC. (Flore Franc, VI., pp. 104-107). 

 Alphitomorpha peniciUaia, Wallr. (Verhandl. Naturf. Freunde, 



I., p. 40). 

 Erysibe penicillata, Lk. (Spec. Plant., VI., I., p. 113). 

 Erysiphe viburni, Duby (Bot. Gall., II., p. 872). 



Erysiphe ceanothi, inbwni, syringie, Sehw. (N. A. Fungi, pp. 269, 270). 

 Microsphxra Hedicigii, penicillata, Friesii, L^v. (Ann. Sci. Nat, Ser. 



III., Tome XV). 

 Microsphxra plakini, Howe (Torr. Bull., V., p. 4). 

 Microsphsera Van Bnmtiana, Ger. (Torr. Bull., VI., p. 31). 

 Microsphsera libimii, Howe (Torr. Bull., V., p. 43). 

 Microsphxra pulchra, C. & P. (Erysiphei of U. S., in Jour, of Bot., 



1872). 



Amphigenous. Mycelium often delicate and evanescent, 

 sometimes abundant and persistent; perithecia usually small, 

 80-1(^0 n, sometimes large, 100-130 /*, wall tissue compact, 

 rather fragile, reticulations not large, 10-15 n; appendages 6 

 or 8 to 15 or 20, hyaline, usually tinted at base, often somewhat 

 roughened, usually about equaling, but varying from less than 

 to more than twice the diameter of the perithecium, 4-6 times 

 dichotomous, branches varying in length and angle of 

 divergence, but always regular and symmetrical, tips acute, 

 distinctly, often strongly, recurved; asci varying with the size 

 of the perithecium from 2 or 3 to 8 or more, usually 4 or 5, 

 ovate when numerous, suborbicular when few; spores 4-8, 

 variable, mostly small, averaging about 20 ^ long. 



On Ceanothus Americanus: Stephenson, Sept. 21, 6082; 

 Ogle, Sept. 22, 6090, Sept. 23, 6135. Euonymus atropurpureus : 

 La Salle, Sept. 17, 1580; Champaign, Aug. 12, 1057. Lonicera 

 flava (cultivated): Champaign, Oct. 9, 2381. Viburnum 

 pubescens: McHenry, Aug. 24, 1262. Viburnum prunifoUum: 

 Jo Daviess, Sept. 18, 5969; Champaign, Oct. (Waite). Ilex 



