282 



FUNGI 



of each of these branches is developed a tiny sporelike 

 body called a sporidium (Fig. 541), which continues the 

 generation of the rust fungus through 

 the next stage of its existence. The fila- 

 ment which bears these sporidia is not 

 parasitic, but when the sporidia ripen 

 and the spores contained in them are 

 scattered by the wind, there begins a 

 second parasitic phase, which forms the 

 most curious part of this strange life 

 history. 



403. The ^cidium. Examine now 

 the under side of your barberry leaves 

 (or comfrey, etc., if red rust is used), for 

 clusters of small whitish bodies that 

 appear under the lens like little white 

 corollas with yellow 

 anthers in the center. 

 More highly magni- 

 fied, this yellow sub- 



stance is seen to be composed of regular 



layers of colored spores. The corolla- 



like receptacles containing them, popu- 



larly known as " cluster cups," are 



u T i i r 



borne on a mycelium produced from 

 the spores described in the last para- 



, r^, . ,. . . . 



graph. This mycelium is parasitic on 

 barberry or other leaves, according to the kind of fungus, 

 and was long believed to be a distinct plant, to which the 

 name sEcidium was given. This term (pi. AZcidia) is 

 now applied to the cluster cups, and those fungi which 

 at any period of their life history produce them are called 

 ALcidiomycetes, ^Ecidium fungi. 



404. Connection between Barberry and Wheat Rust. 



There had long existed a popular belief, both in this country 

 and in England, that the presence of barberry bushes near 

 grain fields produced rust, or mildew, as it is called in Eng- 



541. Teleutospore 

 germinating and form- 

 ing sporidia, s,s, (from 

 COULTER'S " Plant 

 Structures"). 



542. Cluster cups of 



ap p] e rust ( Koste iia), the 

 secidium stage of the 



" cedar apple " fungus. 



