— i3i 



Host-Plant. 



On Trifolium repens (White Clover) 



1 1 > i it 



it < « t < 



" '* incarnatum 



" " pratense (Red Clover) 



" " hybridum (Alsike) . . 



" " involucratum 



11 " Parryi 



11 Glycyrrhiza lepidota 



In 1 888, in the Botanical Gazette, Prof. Underwood writes as 

 follows : ' ' Uromyccs Trifolii appeared in the vicinity of Syra- 

 cuse on Trifolium pratense (Red Clover), and is doing much 

 damage. It is sometimes so abundant that the leaves are half or 

 more dry and dead ; and the damage is 5-20 per cent, on the 

 value of the crop." 



The uredo and teleutospore stages (the Rust proper) were also 

 noticed near Ithaca in 1888, occurring in great abundance. Dur- 

 ing the year 1889, all three stages have been found on the Red 



I, or the cluster-cup stage is also known as the Aecidium stage by botanists; 



II is known as the Uredo stage, and III as the Teleutospore stage. 



The above reference to and explanation of a well-known fungus parasite is 

 made for the purpose of assisting the general reader to better understand 

 the significance of the following study of a parasite very similar to the 

 Wheat Rust in habit and development. Reasoning from analogy, it had been 

 supposed, (before this study was undertaken) that the brown " Clover Rust," 

 consisting of two sorts of spores, (Figs. 6 and 7) corresponding to stages II and 



III (the Red and Brown Rusts) ofthe wheat fungus, were also genetically con- 

 nected with a yellow cluster-cup stage, (Fig. 4) found sparingly on the 

 clover plants. But it was a surmise only, the connection never having been, 

 to our knowledge, experimentally demonstrated. To ascertain the truth of 

 the above theory was one of the objects of this investigation. With that ob- 

 ject in view as well as a determination of its mode of hibernating, its manner 

 of attack on the host in the spring, and a settlement of any collateral ques- 

 tions which might arise, it was determined in the fall of 18S9 to make the 

 Clover Rust the subject of a careful study. 



This work was planned by the undersigned and carried on in his labora- 

 tory ; but the discoveries made and the conclusions reached, and in part 

 stated herein, are the result of the faithful, careful work ofthe author, who 

 as time permits will follow out the incompleted lines of investigation. 



W. R. DUDLEY. 



