Parasitic Fungi of Illinois. 399 



On Rosa sps.: Cook, Sept. 7, 1458; McHenry, Aug. 20, 

 1212; Pulaski. May 5, 4537. Bose stems: Champaign, 

 autumn (Burrill). Rosa lucida: Union, Aug. 20 (Earle). 



Winter (Die Pilze. II., p. 26) and Saccardo (Syl. Fung. I., 

 p. 2) describe this species with hyaline appendages; but Tulasne 

 (Fung. Carp. Select. I., p. 208) describes them as colored. 

 They frequently are colored in our specimens. De Bary 

 (Morph. und Phys. der Pilze, II., p. 48) says " colorless or 

 brown at base." 



S. mors-uvse, (Schw.) B. & C. 

 (Grev. IV., p. 158.) 

 Erysiphe mars-was, Schw. (N. A. Fungi, p. 270). 



Mycelium abundant, at first white, becoming dark brown, 

 densely covering the leaves, stems, and fruit; perithecia most 

 abundant on the stems and fruit, densely aggregated, embedded 

 in the thick felted mycelium, variable in size, 90-120 u. dark 

 brown, reticulations obscure; appendages short, delicate, 

 hyaline or slightly colored, interwoven with and overrun by 

 the dense mycelium: ascus broadly elliptic, eight-spored, both 

 ascus and spores smaller than in S. pannosa. 



On Ribes rot una U 'folium: McLean. July 16. 2373: La Salle, 

 June 16. 5216. Ribes (cultivated): Pulaski, May 8, 4572; 

 L'nion, June 22 (Earle). 



This is the common " gooseberry mildew/' It has been 

 referred to S. pannosa (Bessey. Erysiphei. p. 3, etc.), but it is 

 sufficiently distinguished by its dense, dark-colored mycelium, 

 w r hich is strikingly unlike that of most of the Erysiphew. 



S. pruinosa, C. & P. 



( Erysiphei of the U. S.) 



Hypogenous; mycelium thin, effuse, persistent; conceptacles 

 minute, black; appendages few, long, colorless, sporangium, ovate, eight- 

 spored. 



Leaves of Rhus glabra. Greenbush, August. 



The long colorless appendages readily distinguish the species from 

 the preceding [S. Castagnei, LeV.]. The whole surface of the leaf appears 

 pruinose. — Peck, 25th Eep. X. Y. State Mus., p. 94. 



On Rhus copallina: L^nion, Sept. 17 (Earle). 

 Our specimen is not sufficient for full identification, but it 

 is doubtless the same as that described above by Peck. 



