VIII] UREDINALES 219 



Pucciniaceae^. 



The teleutospores of the Pucciniaceae are provided with a stalk which 

 is often well developed, but is in some cases short or becomes detached at 

 an early stage (deciduous). The teleutospores are one-celled in Uromyces 

 and Hemileia, two-celled in Puccinia and Gymnosporangium ; they are made 

 up of three cells in Triphragmidium, and in Phragmidium of three or more 

 cells. Gymnosporangium is further characterized by the long pedicels of the 

 teleutospores and the fact that they are imbedded in a gelatinous mass. 

 The uredospores are solitary and the aecidiospores produced either in 

 caeomata (^Triphragmidium, Phragmidium), or in aecidia, which in Gymno- 

 sporangium are commonly elongated to form flask-shaped or cylindrical 

 roestelia. 



This family probably includes some of the most highly developed 

 members of the Uredinales, but it includes also several species with caeo- 

 mata, and one, Chrysopsora Gynoxidis, belonging to a monotypic genus in 

 Ecuador, in which the two cells of the stalked teleutospore germinate by 

 internal septation and the protrusion of sterigmata bearing basidiospores 

 as in Coleosporiicni. 



Cronartiaceae 



In the Cronartiaceae the teleutospores are unicellular and sessile, so that 

 they simulate multicellular spores. In Chrysomyxa they form waxy crusts, 

 and in Cronartium a cylindrical body. A pseudoperidium is developed 

 around the aecidiospores. 



The genus Endophyllum is sometimes placed here, sometimes a separate 

 family, the Endophyllaceae, is constituted for it; it differs from the rest of 

 the Cronartiaceae and from the majority of the rusts in the fact that its 

 basidia are developed from spores resembling aecidiospores which arise in 

 an aecidium-like sorus protected by a pseudoperidium. 



Melampsoraceae 



The teleutospores are sessile, loose in the tissue of the host in Uredi- 

 nopsis, in the other members of the family grouped in a flat layer under the 

 epidermis. In Melampsora and its immediate allies they are unicellular ; 

 in other genera, they are divided either vertically into two cells or by 

 cruciately arranged septa into four. 



The aecidiospores may be surrounded by a pseudoperidium or arranged 

 in a caeoma; sometimes a pseudoperidium is present around the uredosorus 

 also. 



' For Bibliography of this and other families, see the end of the group. 



