390 FUNGOUS DISEASES OF PLANTS 



jug-shaped or . cylindrical, with thick-walled peridia. The aecidio- 

 spores are highly colored, and possess numerous germ pores. 

 They are invariably accompanied by flask-shaped spermogonia. 



Gymnoconia. This genus resembles Puccinia in the general 

 characters of the teleutospore, and no uredospores are present. 

 The most abundant spore form is that of the caeoma stage. The 

 latter is an aecidium without a peridium, the spores being borne in 

 chains ; and in this case the spores are generally highly colored, 

 orange to orange-yellow. The spermogonia are numerous, spherical, 

 and very simple in form. 



Phragmidium. The teleutospores are made up of three or more 

 cells in a row borne upon a persistent pedicel. Uredospores are 

 present, and these are borne in pustules bordered by paraphyses ; 

 each spore possesses several germ pores. The aecidia are also of 

 the caeoma type, but here there is an outer border of unicellular, 

 curved paraphyses. The spermogonia are flat or discoidal. Species 

 of this genus occur only upon Rosaceae. 



Chrysomyxa forms a teleutosporic cushion, the cells of which 

 are closely adherent. These spores germinate immediately by the 

 production of a promycelium. The uredospores are borne in chains, 

 as are also the aecidiospores, the two kinds being more or less 

 similar. The aecidia, however, are provided with well-developed 

 peridia. 



^Cronartium is characterized by teleutospores united into a cylin- 

 drical column, each spore germinating immediately by the pro- 

 duction of a promycelium from near the apex. The uredospores 

 are borne singly on pedicels within a semispherical body possess- 

 ing a differentiated peridium. This latter structure is provided with 

 a small terminal pore or mouth. 



Coleosporium. In this genus the teleutospores are closely 

 adherent, with a rounded, thickened, gelatinizing apex. The 

 sterigmata are long, and the sporidia large, ovate, and flattened. 

 The spore, at first a single cell, divides to produce a series of four 

 inner promycelial cells. 



Melampsora. The teleutospores are generally unicellular and 

 closely united into indefinite crusts. The uredospores are borne 

 singly, often interspersed with paraphyses. The aecidia are of the 

 caeoma type, and paraphyses are occasionally present. 



