390 THE FUNGI WHICH GAUSS PLANT DISEASE 



^cidium Persoon (p. 389) 



Spores surrounded by a cup-shaped peridium; produced catenu- 

 late in basipetal series. Germination as in Uredo. 



The species are very numerous and belong in the main to Puc- 

 cinia and Uromyces. Most of the forms of economic interest are 

 found under these genera. A few others of occasional economic 

 bearing whose telial stage has not yet been recognized are given 

 below. 



A. brassicse Mont, on Brassica is perhaps identical with Puccinia 

 isiacae. See p. 378. A. tuberculatum E. & K.^" is reported as 

 destructive on the poppy mallow. A. pelargonii Thum. occurs 

 on geraniums;''"' A. otogense Lindsay on Clematis.'*" A. cin- 

 oamomi Rac. is serious on the cinnamon tree in Java. 



Cseoma Link (p. 389) 



Sori without a peridium, accompanied by pycnia, with or with- 

 out paraphyses, produced in chains. Germination as in Uredo. 



The forms are mostly stages of Melampsora, Phragmidium or 

 their kin. Those of economic interest are found imder Gymno- 

 conia and Melampsora. 



Peridermium L6viellli (p. 389) 



Pycnia tnmcate-conic. ' 



Peridia caulicolous or foliicolous, erumpent, saccate to tubular, 

 lacerate-dehiscent, spores catenulate or at maturity appearing 

 solitary, globose to elliptic or oblong, polyhedral by pressure, 

 yellowish-brown. Epispore always verrucose-reticulate. 



The aecial stages of Coleosporium, Cronartium, Pucciniastrum, 

 Melampsorella and Chrysomyxa. 



The peridia usually extend conspicuously above the host sur- 

 face, and rupture irregularly by weathering. 



All of the species grow on the Coniferae, most of them on Pinus 

 on both leaves, branches and bark. On the leaves the aecia are 

 much of the type shown in Fig. 256. When on the woody parts 

 great distortion may be caused by the perennial fungus and much 

 injury result to the wood (see Cronartium quercus, p. 352). 



The mycelium may live intercellularly in rind, bast and wood 



