80 



(n) Rust of Balsam Firl and F e r n s ( Uredinopsis )-. Several 

 of the fern rusts of the genus Uredinopsis have their spring spore stages 

 on the balsam fir. These stages are usually placed in the form genus 

 Uredinopsis. They are very common on the fir in the coniferous regions 

 of eastern Canada. They are characterized by white spores. The uredo- 

 spcres and teleutospores are commoh on several species of ferns. The at- 

 tacked fronds show w^hite areas. 



(o) Rust of Ash and Marsh Grass ( Puccinia pierider- 



mospora ) . Both stages of this rust have been collected in the vicinity of 

 Ste. Anne's. The spring spore stages occur on the leaves of the ash; the 

 other stages are common on a marsh grass. ( Spartina Michauxiana ) . 



Cross Section of the Trunk of a tree rotted by the White Heart Rot. Fomes iguiarius. (After Von Schrenk.) 



(p) Rust of Bull Pine ( Peridermium Harknesii ) . This is a 

 very destructive rust attacking the bull pine in the Rocky Mountain re- 

 gions. The mycelium is perennial in the infested part and causes large 

 galls on the limbs. It also attacks the stems of young pines and thus soon 

 leadte to their death. The winter spore stage is not known. 



