THE FUNGI WHICH CAUSE PLANT DISEASE 385 



P. phlei-pratensis E. & H. '''*■-"• ^''s-sos 



I. ^'Ecia probably on Berberis, but rarely formed. 



II. Uredinia 1-2 mm. long on leaves and stems, confluent in 

 lines 10 mm. or more long, yellow-brown; spores oblong, pyriform, 

 spiny, 18-27 x 15-19 m- Mycelium perennial. 



III. Telia in leaves, sheaths and stems, 2-5 mm. long or 

 more, confluent, narrow, dark-browTi to black, open or partly 



Fig. 27s. — P. malvacearum. After Holway. 



closed. Spores fusiform or club-shaped, medially constricted, 

 chestnut-brown, apically thickened, 38-42 x 14-16 yu. 



II and III on timothy grass. 



This species is closely related to P. graminis and probably a deri- 

 vate from it, but it does not seem capable of infecting the bar- 

 berry under ordinary conditions.^*^' -''* 



Inoculation experiments with timothy rust at Washington, D. C, 

 show that it can be transferred easily to various grasses. Similar 

 results have been obtained by Eriksson in Europe. It is not a 

 well fixed species and by using bridging hosts it can be made to 



