PUCCINIA 



301 



The uredo and puccinia forms grow on the leaves of sedges 

 (Carex acutd). Judging from the occurrence of the cluster- 

 cup form on the gooseberry in gardens remote from the 

 habitats of sedges it seems probable that this phase of the 

 fungus can reproduce itself without the intervention of the 

 other stages considered as forming part of its life-cycle. 



Aecidiospores globose, epispore hyaline, scarcely wrinkled, 

 contents orange, 10-20 //, diam. 



Teleutospores forming elongated sori on leaves and culms, 

 powdery, blackish ; spores clavate-oblong or oblong, apex much 



FIG. 88. Puccinia pringsheimiana, i, portion of gooseberry 

 leaf with three aecidia or ' cluster-cups ' ; 2, section through a 

 ' cluster-cup ' ; a, spores produced in chains ; b, wall or 

 peridium ; c , epidermis of host ; d, middle cells of leaf ; 

 e, mycelium of fungus ; 3, portion of sedge leaf bearing sori of 

 teleutospores ; 4, portion of same ; 5, teleutospores. 6, uredo- 

 spores. Fig. i nat. size, and remainder variously mag. 



thickened, roundish or truncate, base often narrowed, smooth, 

 brown, 35-50 x 15-20 /x; pedicel rigid, persistent. 



No remedial measures known. It is advisable to pick 

 infected leaves and fruit. 



Klebahn, Zeitschr. Pflanzenkr.^ 5, p. 76 (1895). 



Black rust of cereals. This universally distributed rust, 

 caused by Puccinia graminis (Pers), is the one most injurious 

 to cultivated cereals, attacking wheat, oats, barley, and rye, 



