Parasitic Fimgi of Illinois. 185 



On leaves of Ambrosia trifida: McLean, July 5, 2383, July 

 29, 2336, Aug. 4, 2384; Champaign, Aug. 12 ; 1066; Piatt, Aug. 

 17, 1109; Fulton, Oct. 3, 1734. Xanthium strumarium: Mc- 

 Lean, July 4, 2387, July 6, 2337, July 11, 2388, July 14, 5538; 

 July 29, 2385, Oct. 6, 1796; Tazewell, July 22, 2386; Cham- 

 paign, Aug. 13, 1041; Piatt, Aug. 17, 1128; McHenry, Aug. 

 22, 1205; Lee, Sept. 8, 5719; LaSalle, June 19, 5236, Sept. 12, 

 1477; JoDaviess, Sept. 18, 5985; Rock Island, Sept. 21, 1611; 

 Union, Oct. 21, 1932, Oct. 25, 1993 and 2004; Pulaski, Nov. 4, 

 2249. 



In the specimens on Ambrosia the spores are somewhat 

 thinner walled and more rounded than in those on Xanthium, 

 but the difference is slight. 



P. tanaceti, DC. 



II., III. Amphigenous. Sori mostly rather large, scat- 

 tered, often sprinkled over the entire leaf; uredospores globose 

 to ovate, echinulate, 21-24 by 27-32 (*; teleutospores variable, 

 broadly oblong to broadly oval with rounded ends, usually lit- 

 tle constricted, smooth, or sometimes warty towards the apex, 

 the latter thickened or not, 21-27 by 34-60 ^; pedicel hyaline, 

 very long, two to four times the length of the spore. 



On leaves of Helianthus annuus: Piatt, Aug. 10, 1006; 

 Lake, Aug. 22, 1206, I., II.; Kane, Aug. 30, 1366, I., II.; Cook, 

 Sept. 8, 1468, I., II.; Rock Island, Sept. 27, 1601. H. rigidus: 

 McLean, July 26, 2297, Oct. 11, 1831; Piatt, Aug. 10, 1004; 

 LaSalle, Sept. 12, 1491, Sept. 14, 1539, Sept. 16, 1557, Sept. 20, 

 1598. H. mollis: Marion, Oct. 20, 1902. H. decapetalus: Mc- 

 Lean, Aug. 4, 2299, Oct. 6, 1799. Helianthus sps.: Adams, 

 June 30, 5361, II. ; McLean, July 15, 2301, July 29, 2300, II., 

 III., Oct. 6, 1798, Oct. 7, 1822, Oct. 11, 1837, Oct. 18, 1871; 

 Champaign, Aug. 13, 1038; Piatt, Aug. 17, 1129; McHenry, 

 Sept. 20, 1160; Kane, Aug. 30, 1365; Cook, Sept. 5, 1437; Lee, 

 Sept. 11, 5784; LaSalle, Sept. 13, 1496, Sept. 14, 1541, Sept. 17, 

 1565; Stephenson, Sept. 13, 5835, II., Ill, 5844,11., III.; Jo- 

 Daviess, Sept. 15, 5916, II, III.; Ogle, Sept. 23, 6146, III.; 

 Rock Island, Sept. 21, 1612, II, III, Sept. 26, 1665, Sept. 27, 

 1675; Henry, Sept. 28, 1723; Fulton, Oct. 1, 1766, Oct. 3, 1738; 

 Jersey, Oct. 13, 6291; Union, Oct. 21, 1904, Oct. 28, 2097. 



