390 



Minnesota Plant Diseases. 



remain in the cells of the host. The cluster-cups are found on 



the leaves of some coniferous tree. Spruces in the neighbor- 



hood of affected cow- 



berry plants often show 



an abundance of cluster 



cups and are usually most 



seriously attacked in the 



lower branches. It has 



not been proven in our 



American plants that 



these two stages are con- 



nected, but there seems 



to be considerable proba- 



bility that such is the 



case. 



Rust of a n emone 

 (Puccinia fusca Relh.}. 

 Anemone, Thalictrum 

 and allied genera are sub- 

 ject to the attack of 

 anemone rust. In this rust 

 only the winter spores 

 are produced. The af- 

 fected plants are consid- 



e r a b 1 V deformed. The 

 leaf Stalks are longer and 



the leaf blades are thirk 



ened The SOOre 9TOUOS 



are found on the lower 

 surface of the leaves. The winter spores of the anemone rust 

 pass the winter in a resting condition on the dead leaves of the 

 host and germinate in the spring. 



Rust of wild sarsaparilla (Triphragmium clavellosum Berk.}. 

 Although found only rarely in some places, this rust is very com- 

 mon in others. It is particularly abundant in the northern part 

 of the state, but is exceedingly rare or entirely wanting in the 

 middle and southern parts. It forms blackish, winter-spore 

 groups on the under surface of the leaf. These groups are 

 almost smut-like in their appearance. The spores are com- 



* ^^* ^ e stem rust of cowberry (a plant of 

 the blueberry group). The fungus spores are 

 formed in the skin cells of the host, several in 



each cell; they have 8 erminated sending out 



short, divided threads, each division of which 

 produces a short-stalked basidiospore. Highly 

 magnified. After Hartig. 



