378 



THE FUNGI WHICH CAUSE PLANT DISEASE 



long covered by the epidermis. Spores broadly oval, often 

 almost globose, slightly constricted, apex not thickened, thickly 

 vemicose, brown, 26^8 x 30-35 ii. Pedicels short, colorless, 

 deciduous. Mycelium localized. 



An opsis-type on cultivated Tragopogon. Urediniospores are 

 unknown. The teliospores are often unicellular and are very 

 variable. 



P. tarazaci Plow, is common on dandelion. P. cichorii Pass, is a 

 hemi-type on Cichorium. P. isiacse on Phragmitis is thought to be 



Fio. 274. — P. graminis, telium and germinating 

 teliospore. After Carleton. 



the telial stage of M. brassicae on cabbage. ^*^ P. fagopyri Barcl. 

 is found on buckwheat. 

 P. menthsB Pers. *» 



I. .^cia with peridia immersed, flat, opening irregularly, edges 

 torn; principally on the stems, which are much swollen, more 

 rarely on concave spots on the leaves. Spores subglobose or 

 polygonal, coarsely granular, pale-yellowish, 17-26 x 26-35 li. 



II. Uredinia small, roundish, soon pulverulent and confluent, 

 cinnamon-brown. Spores irregularly rounded or ovate, echinu- 

 late, pale-brown, 17-28 x 14-19 /n- 



III. TeUa black-brown, roundish, pulverulent. Spores ellip- 

 tical, oval, or subglobose, central constriction slight or absent, 

 apex with a hyaline or pale-brown papilla, verrucose, deep-brown, 

 26-35 X 19-23 n. Pedicels long, delicate, colorless. 



An autoecious eu-type on many mints. 



