404 UREDINEAE. 



Spores yellow and polygonal. Leaves when attacked remain 

 broad, short, and pale coloured. 



E. sempervivi (Alb. et Schw.)^ (Britain). The aecidium-lUje 

 patches of teleutospores occur on wijd and cultivated species of 

 Sedum and Uscheveria. The spores produce promycelia from 

 which arise sporidia which germinate on the same host-plant. 

 True aecidia are unknown, but orange-red pycnidia (spermo- 

 gonia) may occur. Leaves of attacked plants are pale and 

 abnormally lengthened.^ 



E. sedi (D. C). Teleutospores occur on species of Sedum. 



The genus P^icciniosira found in Ecuador contains few species, 

 and none of them important parasites. 



Aecidium-Forms 



The relationships of tvhich arc uncertain. 



Aecidium elatinum Alb. et Schw. (Britain and U.S. America). 

 The witches' broom of the silver fir.^ This Aecidium is widely 

 distributed in forests containing silver fir {Abies pectinata), 

 and produces canker of the stem frequently accompanied by 

 that deformation of the branch system known as a witches' 

 broom. 



In Germany it has also been observed on Abies Nm-dvianniana, 

 A. cephalonica, A. Pinsapo ; in North America on A. balsamea ; 

 and in Siberia on A. Pichta. 



As a result of the presence of this fungus, globose or barrel- 

 shaped swellings make their appearance on stems and branches 

 of all ages and on all parts of the trees. A single stem may 

 carry one or many of these, and they continue to increase with 

 its growth. If, as is frequently the case, the bark covering 

 the swelling becomes ruptured and partially detached, then 

 the wood left uncovered becomes a wound, and falls an easy 



'Leveille, Bullet. Science. Natur., xvi., 1825. 



^Illustrated In Kerner's Natural History of Plants, English Edition (Fig. 358). 



'De Bary, Botan. Zeitung, 1867. Weise, "Zur Kenntniss d. Weisstannen- 

 krebses," Mundener Forstliche ffefte, 1891. Heck., " Der Weisstannenkrebs." 

 Springer, Berlin, 1894 ; with Illustrations and Bibliography. 



The canker is common throughout Britain, but witches' brooms have not 

 been often recorded. (Edit.) 



