FUNGI: WHEAT RUST. 



133 



For a fuller study of the wheat rust and of other fungi see the 

 author's larger " Elementary Botany," Chapters XX, XXI. 



Wheat rust. 



Fig. 113- 



Section through leaf of barberry at point affected with the cluster-cup stage of the wheat 



rust; spermagonia above, aecidia below. (After Marshall- Ward.) 



Synopsis. 



A parasite on grains, grasses, and on the barberry. 

 Vegetative part of plant ; mycelium growing within the tissues 



of the host. 

 Fruiting part of the plant. 



1st. Red rust (one-celled spores in pustules on 



blades and stems of the wheat). 

 2d. Black rust (two-celled spores in pustules 

 on the blades and stems of the wheat). 

 F f rm J 3^* Cluster cup (one-celled spores in chains 

 within a structure called a peridium, or 

 cup on leaves and stems of barberry). 

 4th. Spermagonia (small flask-shaped bodies 

 accompanying the cluster cups, of un- 

 known function). 



Material. — Dried stalks of wheat or oats with the black -rust spots ; dried 

 leaves with the red-rust spots ; leaves of the barberry with the cluster cups. 

 (If the barberry leaves cannot be obtained, another species of cluster cup may 

 be used to illustrate the tecidial stage, but it should be remembered that other 

 cluster cups are not connected with the life history of the wheat rust. ) 



For satisfactory studies of the cluster-cup stage, sections through the cup 

 should be made from fresh material, or sections already made may be pur- 

 chased from the supply companie$. ^ 

 Microscope, etc. 



