104 



SHADE TREES. 



Fig 39. White Pine Blister Rust. A. A four-year-old tree with 

 the disease; B. Leaf of Ribes aureum showing uredospore 

 stage; C. Portion of same enlarged; D. Leaf of 

 Ribes nmericanum showing teleutospore stage. 

 (From Bui. 206, Bureau of Plant In- 

 dustry, U. S. Dept. Agricul.) 



