334 UREDINEAE. 



U. appendiculatus (Pers.), [U. phaseoK (Pers.)]. On species 

 of Fhaseolus. (Britain and U.S. America.)' 



U. primulae Lev. On Frimula hirsuta. 



U. limonii (D. C). On Armeria and Statice. (Britain and 

 U.S. America.) 



IJ. polygoni (Pers.). On Polygonum and Riimex. (Britain 

 and U.S. America.) 



U. acetosae Schroet. On Bumex. 



U. silenes (Schlecht.). On Silene and Dianthus. 



U. euphorbiae (Schwein.). On Euphorbia Preslii in Italy, 

 and some other species in America.^ 



U. geranii (D. C). On Geraniums. (Britain and U.S. America.) 



U. betae (Pers.). On Mangel Wurzel and Beta. (Britain 

 and U.S. America.) 



U. pamassiae (D. C). (Britain.) 



U. salicomiae (D. C). (Britain.) 



U. Valerianae (Schum.). On Valeriana dioica (Britain). 



(2) Bycnidia (spermogonia) and a^cidia produced on one host; the 

 related uredo- and teleutospores on another host : 



Uromyces pisi (Pers.) (Britain) Pea-rust. The uredospores 

 and teleutospores are developed in various species of Bisum, 

 Lathyrus, and Vicia. The teleutospores are finely punctured. 

 The aecidia appear on the under surface of the leaf of Euphorbia 

 Cyparissias, and are preceded by pycnidia. 



Attacked plants of Euphorbia become completely changed in 

 their appearance. The stems are much elongated, and as a 

 rule remain unbranched. Flowers are seldT)m or never produced ; 

 if so, they are permeated by mycelium and deformed. The 

 leaves are short, thick, and rounded-off; they have a pale-green 

 colour, and are distant from each other on the shoot. Their 

 internal structure is also considerably modified. Wakker states 

 that the cells of the mesophyll become enlarged, while no 

 coUenchyma is developed in the ribs. Fentzling* gives the 

 following changes : the epidermal cells become broader ; stomata 

 are more numerous on the upper surface of the leaf, and fewer 

 on the lower ; the laticiferous tubes below the upper leaf- 



1 Description, illustration, and treatment in iV. York Agric. Exper. StcUion. 

 Bull., 48, 1892. 



2 Magnus, Berichte d. deutsch. botan. 6es., 1893. 



' " Untersuchung d. Veranderungen welche durch Rostpilze hervorgerufen 

 werden." Inaugural Dissertation. Freiburg, 1892. 



