Parasitic Fungi of Illinois. 215 



July 25, 2508, IT., Aug. 28, 5642, Oct. 6, 1809, TIL, Oct. 18, 

 1884, III.; Piatt, Aug. 10, 1003, II.; Champaign, Aug. 41, 

 1019, II., Oct. 31,6376; Lee, Sept. 9, 5751,11.; LaSalle, Sept. 

 13, 1508, III., Sept. 17, 1586, II.; JoDaviess, Sept. 15, 5909, 

 II, III.; Henry, Sept. 28, 1722, IL, III.; Fulton, Oct. 1, 1784, 

 III.; Jackson, Nov. 5, 2261,111. 



COLEOSPOBIUM, Ltiv. 



Teleutosori divided by horizontal septa (about three) so 

 ;is to form unbranched vertical rows of closely connected cells, 

 each of which emits, on germination, a promycelium bearing a 

 single sporidium, compacted in a dense flat or convex some- 

 what waxy stratum; uredospores produced in chains, which 

 soon break up into a powdery mass; sorus naked. 



The species of this genus are difficult to determine mor- 

 phologically one from another, and comparatively little has 

 been done towards elucidating life histories through cultures. 

 It is supposed that Coleosporium senecionis and Peridermium 

 pini are alternate forms of one species, but other aecidial states 

 are unknown. The so-called uredospores are produced in 

 chains, and according to the classification adopted here would, 

 by themselves, fall in the genus Cceoma. The query arises as 

 to whether this should be looked upon as the aecidium or uredo 

 stage. So far as observed this form grows on the same leaf, 

 and usually just before the teleutoform, characteristics of the 

 latter rather than the former. If, indeed, Peridermium pint is 

 the secidium form of Coleosporium senecionis, then the pulver- 

 ulent spores on Senecio, one would say, must be the uredo 

 form, and these are very similar to the first-formed spores of 

 the other species. 



C. sonchi-arvensis, (Pers.) Lev. 



II, III. Hypogenous, rarely epiphyllous. Uredosori scat- 

 tered or united in groups, often very numerous and sometimes 

 crowded or confluent, elliptical or irregular, powdery; uredo- 

 spores elliptical, often irregular, thickly studded with little 

 obtuse tubercles, orange-yellow, but soon fading, 15-21 by 

 16 



