58 



MEL LMPSORA I'IMTi > K < t > I " A 



point, combined with this lateral curvature, causes S-shaped 

 <li>turti<.ns which have given rise to the name "Pine Branch 

 Twist" for the disease (Fig. 35). 



It is suggested by Massee that the secidiospores can repro- 

 duce the secidia ;in<l thus propagate the parasite <>n the Pine 

 u ii limit reference to the alternate hosl . bul do proof is given of 

 i his statement. The mycelium is almost certainly perennial 

 in the affected branch, and thus fresh outbreaks arise year by 

 year more or less, according to the weather in the spring. 



If the a-cidiospores are blown on to a leaf of Aspen, they 

 germinate there and the mycelium produces uredospores during 



Fig. 35. Melampsora pinitorqua (from a German specimen, ex herb. 

 Sydow). a, a young shoot of Pine, in June, with newly-formed 

 leaves, showing three ca?omata (<e), shaded ; the leaves have been 

 removed from the affected portion, which is beginning to be curved; 

 b, a caeoma. x 10; c, ascidiospores; d, old leaf of Aspen, showing 

 numerous teleuto-sori on the lower surface; e, teleutospores. 



the summer: these are usually so abundant as to cover the 

 underside of the leaves, and the parts or which they occur show 

 plainly as yellow spots on the upper side. For a time, the 

 uredospores spread the disease rapidly during the growing 

 season, until sometimes all the leaves of a tree are more or less 

 attacked and are covered with a bright orange powder. As 

 the leaves begin to die, teleuto-sori are formed ; at first these 

 are brown, and show as little angular crusts on the under side. 

 Afterwards, when the leaves are fallen off, the crusts begin to 

 turn almost black as the teleutospores mature. These spores 

 are produced beneath the epidermis, standing erect and side by 



