518 FUNGI IMPERFECTI. 



as important parasites. Amongst these are the following British 

 and North American species : 



M. brassicae Berk. On cabbage, generally somewhat decayed. 



M. sarcinula Berk. On cucumber. 



M. nobile Yize. On Dianthus. 



M. alliorum Cke. et Mass. On onion. 



M. ramulosum Sacc. On celery. 



M. catalpae Ell. et Mart. On Catalpa Bignonioides. 



M. nigricantium Atks. is a semi-parasite accompanying other diseases 



of the cotton plant. 



Mystrosporium. 



"Allied to Macrosporium, but distinguished by the more rigid 

 and darker-coloured hyphae and conidia " (Massee). 



Mystrosporium abrodens Neumann. 1 This is described as 

 the cause of a disease which destroyed one-tenth of the total 

 wheat-crop in the Haute- Garonne of France. The fungus 

 attacked the nodes and leaves, forming dark patches ; the nodes 

 were weakened and frequently broke over, while the ears were 

 badly developed. 



Alternaria. 



Conidia grey, muriform-septate, flask-shaped, and borne on 

 short simple conidiophores. 



" Distinguished by the clavate or flask-shaped muriformly 

 septate olive conidia being united in chains and connected 

 by narrow isthmus-like portions " (Massee). 



Alternaria brassicae (Berk.) (Britain). This species causes 

 on leaves roundish black spots marked with concentric brown 

 zones. The mycelium lives in the leaf-parenchyma and gives 

 off tufts of conidiophores through the stomata. Briosi and 

 Cavara state that it causes considerable damage to Brx*i<-tt 

 <>/<,ricea, Coclilearw officinalis, and Armoracia. (Probably tin- 

 same species as Polydcsmus cxitiosus Kuhn.) 



Other diseases have been ascribed to species of Alt<-ni"ri". 



Septosporium. 



Conidia brown, and muriform-septate. Conidiophores of two 

 kinds short and fertile, or elongated and sterile. 



Septosporium heterosporum Ell. et Gall, causes a leaf- 



1 "Un nouveau parasite de ble." Societe de Bioloy. a Toulouxe, 1892. 



