STEVENS: DISEASES OF GRASSES. I3I 



tissues and using up the rich food supply sent up for the formation of 

 the fruit. In this class the effects appear to be entirely local, the 

 nutrition of other parts of the plant not being impaired. Claviceps 

 purperea is a type of this class of parasites. 



Many parasitic fungi have a wide range of host plants, and this fact 

 must at times be considered by economic mycologists in devising pre- 

 ventive methods. It is quite likely that in some instances mistakes 

 have been made in classifying similar forms on different hosts as 

 identical. A study of the development of these forms in nutrient 

 media, such as has already been done by Brefeld, will help to make a 

 safer basis of classification. To illustrate the wide range of which 

 some parasites are capable, I have arranged from Farlow & Seymour's 

 Host Index a list of the Graminese which serve as hosts for a few of 

 the parasites of frequent occurrence on some of our cultivated cereals. 



Claviceps purpurea, (Fr.) Tul. 



Agropyrum divergens, Nees. 



" glaucum, Roem. & Schult. 



" repens, L. 



/ " violaceum, Lange. 



Calamagrostis Groenlandica, Kunth. 

 Elymus Canadensis, L. 



" condensatus, Presl. 



" Virginicus, L. 

 Glyceria fluitans, R. Br. 

 Hordaum jubatum, L. 

 KcBleria cristata, P. 

 Phalaris arundinacea, L. 

 Poa sp. indet. 



Spartina cynosuroides, Willd. 

 Tripsacum dactyloides, L. 

 Triticum vulgare, L. 



ERYSIPHE CRAMINIS, DC. 



Agropyrum glaucutn, Roera. & Schult. 



Agrostis exarata, Trin. 



Avena sp. indet. 



Beckmannia erucaeformis, Host. 



Elymus condensatus, Presl. 



Glyceria nervata, Trin. 



Hordeum jubatum, L. 



Poa pratensis, L. 



" tbnuifolia, Nutt. 

 Triticum vulgare, L. 



PiRicuLARiACRiSEA, (Cke.^ Sacc. 



Leersia oryzoides, Swz. 



" Virginica, Willd. 

 Muhlenbergia glomerata, Trin. 

 Panicum dichotomum, L. 

 Poa pratensis, L. 

 Setaria glauca, Beauv. 



" Italica, Kunth. 



