214 Illinois State Laboratory of Natural History. 



M. salicina, Lev. 



II., III. Amphigenous, the uredo mostly hypophyllous, and 

 the teleutoform more often epiphyllous. Uredosori small, cir- 

 cular, often thickly spread over the leaf surface, surrounded hy 

 a thick row of paraphyses, which are strongly enlarged and 

 rounded above; uredospores subglobose or elliptical, finely 

 echinulate, 12-15 by 14-18 /*; teleutosori various in size, usu- 

 ally flat, irregular, often thickly associated or confluent, crust- 

 like, becoming reddish brown or dark brown; teleutospores ob- 

 long, in transverse section polygonal, about 10 by 30-87 ^. 



On leaves of Salix cordata: McHenry. Aug. 23, 1242, IT.. 

 Aug. 24, 1276 and 1271. S. longifolia: McHenry, Aug. 24, 

 1254, II., Aug. 31, 1396, IT., TIL; Lake, Aug. 27, 1350, II., TIL: 

 Lee, Sept. 11, 5780, II.; LaSalle, Sept. 14. 2500, II., III.; Henry. 

 Sept. 28, 1707, II. Salix sps.: McLean, July 18, 2498, II., 

 July 20. 2497, II., Aug. 4, 2499, II.; Piatt,-Aug. 17, 1096, II.; 

 McHenry, Aug. 24, 1278, II., 128S, II.; Lake, Aug. 27, 1351, II., 

 III.; Kane, Aug. 30, 1375, II., Ill,; LaSalle, Sept. 20, 151)1). 

 II., III.; Rock Island, Sept. 21, 1618, II.; Jersey, Oct. 14, 6315, 

 II., III.; Union, Oct. 24, 1977, II.; Pulaski, Nov. 4, 2228, II., 

 III. 



Thiimen thinks what is included in the above should be 

 separated into the following species, for which he has given 

 descriptions: M. Biglowii, M. capreanum, M. Hartiyn, M. 

 medusce, M. vitellince, (Hedwigia XVIII. [1879] p. 77, and Bul- 

 letin Torrey Botanical Club, VI. p. 216). 



M. populina, Lev. 



II., III. Amphigenous. Uredosori small, scattered over 

 the surfaces of the leaves, usually more numerous below, 

 circular, surrounded by a dense row of paraphyses, which are 

 clavate or strongly enlarged and rounded above, powdery, 

 orange-yellow; uredospores varying from subglobose to oblong 

 or clavate, echinulate, 13-20 by 21-30 /* ; teleutosori scattered, 

 mostly thickly studding both surfaces of the leaf, flat, compact, 

 crust-like, often confluent, reddish brown; teleutospores oblong, 

 prismatic, epispore thin, smooth, one-celled, 15 by 36-45 u. 



On leaves of Popiilits tremuloides: McHenry, Aug. 20. 

 1196. P. nionllifera: Tazewell, July 22, 2509, II.; McLean, 



