MELAMPSORA 



:;:>:! 



l>v looking in spring on fallen leaves of /'. tremula, /'. alba, at places where 

 Mercurialis is found to be affected. The caeoma on the latter is very 

 capricious in its occurrence ; in some years it may be found almost every- 

 where, in other years hardly a specimen can be met with. The large 

 yellow spots show conspicuously on the upper surface of the leaves, so 

 that when it does occur it is impossible to overlook it. 



There are two places near Birmingham where all the spore-forms occur 

 year after year in close proximity : it is from these specimens that the 

 descriptions are taken. In one case the teleutospores are on P. alba, in 

 the other on /'. trenvula. 



The morphological differences of the four (or five) species of Melam- 

 psora which appear on P. alba and P. tremula are very slight. It is better 

 tn include them all for the present under Melampsora tremulae, as 

 biological races. The fourth species is M. Magnusiana Wagner, which 

 has its ceeomata on Chelidonium, and which, according to Klebahn, is 

 identical with M. Klebahai Bubak, on Gorydalis ; this has not yet been 

 recorded for Britain, but Plowright mentions (I.e. p. 241) a Melampsora 

 in) P. tremula from which he could not obtain cajomata on either Larix or 

 Pimcs or Mercurialis — this might be M. Magnusiana. 



12. Melampsora Euphorbiae Cast. 



Credo Helioscopiae Pers. Disp. Meth. p. 13. 



Lecythea Euphorbiae Lev. ; Cooke, Micr. Fung. p. 221. 



Melampsora Euphorbiae Cast. Obs. ii. 18, with plate (1843). Cooke, 



Handb. p. 523 ; Micr. Fung. p. 219, pi. 9, f. 193, 194. 

 M. Helioscopiae Wint. Pilze, p. 240 (1884). Plowr. Ured. p. 236. 



Save. Syll. vii. 586. Fischer, Ured. Schweiz, p. 508, f. 318. 



| S/^rmogones. Flat, hemispherical. 



Jk-idiospores. Cseomata minute, \ — h, mm. diam. on the 

 leaves, 1 — 4 mm. lung on the stems, yellowish-red; spores in 



i-'i.'. -'(it. 



G. U. 



M. Euphorbiae. a, teleutospores on E. exigua ; b, teleutos-porc, 

 and c, uredospore and paraphysis, on E. Peplus. 



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