78 



(d) The Rust of Balsam Fir and Blueberry ( Calyp- 



tospora columnaris ) . The aecidiospores are produced in the leaves of the 

 balsam fir, but no spermatia are formed. The spring spores reach the 

 blueberry and attack them. The infected stems assume a brown, shining 

 swollen appearance and are almiost destitute of leaves. The teleutospores 

 or winter spores are produced in immense numbers in the epidermal cells 

 of the swollen stems. The mycelixmi is perennial in the blueberry and 

 spore production takes place each year without new infection. Uredo- 

 spores are never formed. 



Beech Tree with Fruiting Bodies of Fomes Fomentarius (After Von Schrenk). 



(e) Rust of Spruce and Labrador Tea ( Melampsorop- 



sis ledicola) The spring spores of this species are sometimes so abundant 

 on young spruces that they present the appearance of having been swept 

 by fire. These spores carry the fungus to the Labrador tea ( lycdum groen- 

 landicum ) .The mycelium lives in the leaves of this plant till the follow- 

 ing spring and in June abundant teleutospores are produced on the upper 

 side of the leaves. These germinate on the leaves and produce sporidia 

 which are carried by the wind to the neighbouring spruces. The aecio- 

 spores are usuailv mature on the lea\ies of the spruces by the middle of 

 July. 



