280 



MANUAL OF POISONOUS PLANTS 



Fig. 99. Black Spot of Grasses (Phyllackora graminis). A. 

 Cross section of leaf through a black mass of the fungus. P. 

 Perithecia. B. An ascus with ascosnores. a, b. Spots on grass 

 leaf caused by the fungus. After Frank and Trelease. 



Phyllackora graminis (Pers.) Fckl. 



Stroma scattered or confluent, penetrating the leaf and more or less prom- 

 inent on both sides, covered by a black and shining epidermis, roughened ; 

 ostiola obscure; asci short, stalked, cylindrical, 75-80 x 7-8 f^, ascospores 8, 

 paraphyses present. 



Phyllackora graminis, occurs on many cultivated and wild grasses; other 

 species occur on clover and other leguminous plants. This parasitic fungus 

 disease causes blackish spots on the lower or both surfaces of the leaf. The 

 fungus causing these black spots on grasses has been called the black spot 

 disease. 



During August, and especially later, the coal black spots along the veins 

 are especially prominent; they are considerably less than one-eighth of an inch 

 in length and width and occur on both surfaces of the leaf, but are more 

 abundant on the upper. These black spots are composed of dense mycelium, 

 which in the green leaves bears numerous small spores which serve to proga- 

 pate the fungus in the summer. In dead leaves, small perithecia are found, 

 which contain numerous elongated bodies, the asci, within which are found eight 

 small, colorless spores, known as ascospores; these latter carry the fungus over 

 winter. 



Distribution and Hosts. Widely distributed in both Europe and North 

 America, very coinmon upon Quack Grass, Wild Rye, Bottle Grass, Panic 

 Grass, etc. 



Poisonous properties. Tlie genus Phyllachora is abundant at times and is 

 associated with stomatitis. 



SPHAEUlALES 



Perithecia generally with a distinct ostiolum, of various consistencj', not 

 reddish or membranous, brown or blackish ; stroma when present dark colored 

 outside and whitish within. Contains the families: Sordarlaccac, found upon 

 decaying plants and substances; Ckaetomiaccac, with superficial perithecia, gen- 



