I'di'dsif/i- Fioiijl of Tlliiioia. 215 



July 25, 2508, U., Au<,^ 28, 5642. Oct. (>, ISOV), ITF., Oct. IS. 

 1884, in.; Piatt, Aug. 10, 1008, If.; Champaign, Aug. 41. 

 KUl), IT.. Oct. 31, 037f5; Lee, Sept. 9, 5751, II.; LaSalle, Sept. 

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

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

 III.: Jackson. Nov. 5. 22()1, III. 



COLEOSPORIUM, Lkv. 



Teleutosori divided by horizontal septa (ahout three) so 

 as to form unhranched 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 Coho^pofinni senecloiiis and Perideniiiinii 

 p'nii are alternate forms of one species, but other ajcidial 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 Cceoiiia. 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, Periderniiuin pint is 

 the tecidium form of Coleosporhmi 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 s])or(>s 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 sometiuu's 

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

 spores ellijitical. often irreguhir, thickly studded with little 

 obtuse tu])ercles, orange-yellow, but soon fading. 15-21 by 

 16 



