COLEOSPORIUM 



323 



Teleutospores. Sori filling large intercellular spaces of the 

 mesophyll towards the lower sur- 

 face of the leaf; spores prismatic, 

 length up to 140 /x, breadth 18 — 

 28 /a; epispore 18 — 21 /a thick, or 

 more, at the summit. 



iEcidia on (?both) leaves of 

 Pin us silvestris; uredo- and teleu- 

 tospores on Tussilago Farfara, 

 May — November, very common. 

 (Fig. 243.) 



Fig. 243. G.Tussilaginis. iEcidia 

 oq both leaves of a fascicle of 

 P. silvestris (from Blackmail's 

 experiment), reduced; uredo- 

 and young teleutospore x 600. 



The connection of the spore-forms 

 on the alternate hosts has been demon- 

 strated by Plowright, Klebahn, Fischer 

 and Wagner. Klebahn and Fischer 

 showed moreover that the parasite can- 

 not be transferred to Petasites or Sonchus. 



Plowright produced the secidia (P. Plowrightii) on leaves of Scots Pine 

 from the Coleosporium on Tussilago (experiment 1243), 25th May, 1899. 

 His specimens show the peridia, in almost every case, on both leaves of 

 the fascicle. The same is true of the following experiment by Blackman : 

 In October, 1904, he tied leaves of Coltsfoot bearing germinating teleuto- 

 spores of C. Tussilaginis on four trees of P. silvestris at Crockham Hall, 

 Kent. On April 14th, 1905, the beginnings of spermogones and secidia 

 were visible in three cases on neighbouring needles, but nowhere else. In 

 June, 1905, all four showed the Peridermium. Specimens in Herb. Kew. 



The uredospores are often very densely and rather coarsely verruculose, 

 but also occasionally smooth either wholly or in parts ; in fact the warts 

 are deciduous and may disappear entirely. 



Distribution : Europe. 



3. Coleosporium Petasitis Lev. 



Coleosporium Petasitis Lev. Ann. Sci. Nat. 1847, p. 373. Cooke, 

 Handb. p. 521 ; Micr. Fung. p. 217. Fischer, Ured. Schweiz, 

 p. 450. 



C. Soncld Plowr. Ured. p. 250 p.p. Sacc. Syll. vii. 752 p.p. 



Peridermium Boudieri Fischer, Contrib. etude du genre Coleosporium, 

 in Bull. Soc. Bot. Fr. xli. 171. 



sEcidiospores. iEcidia (P. Boudieri) like those of neigh- 

 bouring species. 



21-2 



