48 



Very common and destructive. Often covering the entire 

 under surface of the leaf. 



PUCCINIA POLY<;ONI AMPIIIUII, Pers. II & lit. On water 

 persicaria (Potygonum amp/iibmm), and tan weed (P.otygonwm 



terrestre). This species is very common, and also very de- 

 structive. It appears on the under side of the leaves, some- 

 times scattered indefinitely over the surface, but usually in 

 more or less circular spots. 



PUCCINI A FRENANTIIIS, (Pers.) Fuckel. I, II & III. On wild 

 lettuce (Lactuca pulchella). Common and destructive, especi- 

 ally in the first stage, which is usually found along the mid- 

 ribs of the leaves. The affected plants assume a much more 

 upright mode of growth than their fellows, and seldom ripen 

 many seeds. 



PUI;CINIA TAKAXACI, Plow. Dandelion rust. II <fe III. On false 

 dandelion (Troximon glancum). Not common and not very 

 injurious. What is probably the same thing has been collect- 

 ed several times on common dandelion (Taraxacum officinale), 

 upon which host it is much more destructive. 



PUCCINIA XANTHII, Schw. Cockle bur rust. III. On common 

 cockle bur (Xanthium canadense). Forms large, swollen 

 brownish places on the under surface of the leaves. It is 

 quite common and frequently becomes very destructive. 



PHRAGMIDIUM SPECIOSUM, Fr. Stem rust of the rose- II & III. 

 On wild rose (Rosa arkansana). Very common and destructive. 

 JSta^e II appears usually in June on the younger stems, 

 petioles, and sometimes, leaves, buds and fruit, forming lartre,. 

 bright orange masses of spores. Stage III appears later as 

 a black, powdery mass upon the stems. 



PHRAGMIDIUM suBCORTiciuM,(Schraiik) Winter. Rose leaf rust. II 

 & III. On leaves of wild rose (Rosa, arkansana). Not uncom- 

 mon, and sometimes becoming destructive. Sori scattered 

 over the under surface of the leaf, giving it a powdery ap- 

 pearance- This species has been known to be quite in- 

 jurious to cultivated roses, but so far, it has been found here 

 only on wild roses. 



