CRYPTOGAMS 



193 



Rye, Oats, and various other grasses. The first appear- 

 ance of this Fungus in the spring that one is at all likely 

 to see, however, is not upon a grass, 

 but on the leaves of the common 

 Barberry, in the form of thick- 

 ened red patches. On the under 

 side of these areas, embedded in 

 the leaf tissues, are then found the 

 so-called cluster cups, or fructifica- 

 tions (Fig. 319), 



filled with chains 



of rounded spores. 



New spores are 



formed at the base 



of the chains while 



the terminal ones 



fall off and are 



carried by the winds to the Wheat (or 



other grass). The mycelium produced 



from these spores penetrates the body 



of the new^ host, 



where it increases 



largely, working 



damage to the 



Wheat, and form- 



tsp 



319. Section through a clus- 

 ter cup of Puccinia in 

 the leaf of Barberry. 



320. A stalk of grass 

 with spores of 

 Puccinia break- 

 ing through the 

 epidermis in 

 dark patches. 



ing at the surface 



masses of spores 



for the further 

 spread of the disease. The spores 

 produced on the Wheat are differ- 

 ent both in shape and in the manner 

 in which they are borne from the 

 spores of the cluster-cup stage on 

 Barberry. Moreover, on Wheat 

 the spores are of two sorts (Fig. 

 321) : (1) unicellular uredospores^ 

 prevailing until late summer or fall, the office of which is to 

 spread the Rust by immediate germination on being blown 



OUT. or BOT. — 13 



321. Uredospores and a te- 

 leutospove (0 of Puc- 

 cinia. — De Bary. 



