262 THE FUNGI WHICH CAUSE PLANT DISEASE 



P. tritici-repentis Died, is found on Triticum repens (=Agropy- 



ron repens.) Conidia=Helminthosporium tritici repentis. 



P. trichostoma (Fr.) Wint. ( =Pyrenophora trichostoma (Fr.) 

 Sacc.2*2 



Perithecia gregarious, innate, conical, black, ostiole surrounded 

 by black hairs, which are simple, septate, 6-8 n in circumference; 

 asci clavate 300 x 40 /i; spores broadly oblong, obtuse, unequally 

 4 to 6-septate, muriform, brownish, 52 x 20 /x; paraphyses branched. 



On rye with the conidial form =Alternaria trichostoma Died. 



In the present state of our knowledge little is to be gained by 

 recognition of these purely "biologic species," and all the forms 

 may be grouped under the name P. trichostoma, recognizing the 

 fact that it shows biologic differentiation. 



Two hypothetical forms P. teres Died, and P. avenae Died, 

 pertain to Helminthosporiums of corresponding names. 



Massariacese (p. 223) 



Stroma none; perithecia separate, sunken, not erumpent, open- 

 ing by a small pore, leathery or carbonous, compact; spores usually 

 surrounded bj-^ a jelly-like substance; paraphyses present. 



This family of ten genera and about one hundred twenty-five 

 species contains only one parasite of interest. 



Key to Genera of Massariaces 



Spores 1-celled 

 Spores not surrounded by a jelly-like sub- 

 stance 1. Enchnoa. 



Spores surrounded by a jeliy-liko sub- 

 stance 2. Pseudomassaria. 



Spores several-celled 

 Spores not muriform 

 Spores hyaline or yellow 

 Spores ellipsoid to spindle-shaped, 



several-celled, hyaline 3. Massarina. 



Spores spindle-formed, curved, 3 to 4- 



celled, yellow 4. Ophiomassaria. 



Spores 2 to 4-celled, elongate, )\yB.- 



luie 5. Charrinia, p. 263. 



