THE FUNGI WHICH CAUSE PLANT DISEASE 589 



Hyphae verticillate; sterile hy- 



phaB present 13. Mucrosporium. 



Parasitic 



Conidia mucose-conglobate, allan- 



toid, often continuous 14. Allantospora. 



Conidia not mucose-conglobate 

 Conidia ovate-cylindric or elon- 

 gate, often catenulate 15. Ramularia, p. 590. 



Conidia obclavate-pyriform 16. PirictJaria, p. 591. 



Septocylindrium Bonardin (p. 588) 



Coiiidiophores very short, scarcely distinct from the conidia, 

 or in parasitic species distinct but short and inflated or dentic- 

 ulately sublobate at the apex; conidia oblong or cylindrical, one 

 to many-septate, catenulate, the chains often branched. 



About thirty species, a few of them of economic impor- 

 tance. 



S. areola (Atk.) P. & C.^^^' "^^ 



Spots amphigenous, pale, becoming darker in age, 1 to 10 mm., 

 angular, limited by the veins of the leaf, conidiophores amphig- 

 enous, fasciculate, sub- 

 nodose, branched or not, 

 several times septate, 

 hyaline, 25-75 x 4-7 jti; 

 conidia oblong, usually 

 abruptly pointed at the 

 ends, catenulate or not, 

 14-30 X 4-5 M, hyaline. 



Leaf spots are pro- 

 duced on cotton. The Fig. 394.-S. areola. After Atkinson. 



conidia and stalks are so abundant on the undersides of spots as 

 to give them a frosted appearance. 



S. rufomaculans (Pk.) P. & C. 



Spots numerous or confluent and even covering the entire leaf, 

 reddish; conidiophores very short, hypophyllous, cespitose; conidia 

 catenulate, variable, ellipsoid-oblong to cylindric, hyaline, 8-16 x 



3-4 M- 



It is somewhat injurious on buckwheat in America.^®* 



