334 UREDINEAE. 



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

 of FJ/i'siii/i/s. ( P)ritaiii ami U.S. America.)^ 



U. primulae Lev. On Primula hirsuta. 



U. limonii (I). C). On Armeria and Siatice. (Britain and 

 U.S. America.) 



U. polygoni (Pers.). On Poljjgonum and Bumc.c (Britain 

 and U.S. America.) 



U. acetosae Schroet. On Rumrx. 



U. silenes (Schlecht.). On Sllcne and Dianfhus. 



U. euphorbiae (Schwein.). On Bxjjhorhia Freslii in Italy, 

 and Sduie other species in America.- 



U. geranii (1). C). On Geraniums. (Britain and U.S. AmeritA.) 



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

 and U.S. America.) 



U. parnassiae (D. C). (Britain.) 



U. salicorniae (D. C). (Britain.) 



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



(2) Pycnidia {spermogonia) and aecidia produced on one host; the 

 related, itredo- and teleutospores on another host : 



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

 and teleutospores are developed in various species of Plsum, 

 Lcdhyrus, and Vicia. The teleutospores are finely punctured. 

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

 Gyparissias, and are preceded by pycnidia. 



Attacked plants of Euphorhia become completely changed in 

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

 rule remain unbranched. Flowers are seldom 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 

 collenchyma 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- 



^ Description, illustration, and treatment in -V. York Agric. Exper. Station. 

 Bull., 48, 1892. 



-Magnus, Berichte d. deutsch. holan. (7es., 189.S. 



* " Untersuchung d. Veriinderungen welche durch Rostpilze licrvorgerufen 

 warden. " Inaugural Dissertation. Freiburg, 1892. 



