570 THE FUNGI WHICH CAUSE PLANT DISEASE 



O. mespilinum Thiim on Mespilus; 



O. tabaci Thiim on tobacco; 



O. verbenae T. & B. on Verbenas. 



O. quercinum Thiim has been reported as the cause of much 

 injury to oaks in Europe since 1907. The identity of the Oidium 

 causing the epidemic is, however, much questioned. By some it is 

 regarded as a stage of Microsphaera alni, by others it is set up 

 under a separate name as O. alphitoides G. & M.^^** ^^^ 



Hartigiellese (p. 566) 



One genus, Hartigiella Sydow. The species H. laricis (Hart.) 

 Syd. causes fall of needles of larch.^^' 



Cephalosporiese (p. 566) 



Hyphae elongate; conidia in heads. 



Key to Geneka of Cephalospories 



Conidia globose or oblong 

 Conidia sessile on the head or nearly so 

 Fertile hyphae inflated at apex 

 Apical vesicle globose-inflated 

 Conidia sessile, not mucus-covered 

 Vesicle verrucose or muriculate 



Fertile hyphse simple 1. (Edocephalum. 



Fertile hyphae sigmoid, much • 



branched 2. Sigmoideomyces. 



Vesicle hexagonally areolate. ... 3. Rhopalomyces. 

 Conidia on stalks, mucus-covered. 4. Gliocephalus. 

 Apical vesicle clavate or lobed 

 Vesicle disk-shaped, stellate- 



lobed 5. Coronella. 



Vesicle clavate or subpalmate. ... 6. Buseella. 

 Fertile hyphae not inflated at apex 

 Conidial head covered with mucus 



Fertile hyphae simple 7. Hyalopus. 



Fertile . hyphae with verticillate 



branches at tip 8. Gliobotrys. 



Conidial head without mucus 

 Fertile hsrphse with one head 

 Conidia not separating 9. Papulospora. 



