156 Illinois State Laboratory of Natural 



III. Spores at maturity in a dense, waxy or crust-like stratum, 

 not separating from each other. 



A. Spores one-celled, less commonly several-celled, and 



then the septa almost never horizontal, mostly dull 

 reddish brown. 



1. Spores one-celled, oblong, united in an erect (often 



curved) cylindrical column CRONARTIUM. 



2. Spores one or more celled, septa, when present, 



mostly vertical or oblique, united in a flat or 

 convex stratum MELAMPSORA. 



B. Spores several -celled, septa horizontal, mostly reddish- 



orange. 



1. Spore cells short (not longer than wide), united 



in a flat waxy mass, cell rows simple. 



COLEOSPORIUM. 



2. Spore cells oblong or cylindrical, in simple or 



branched vertical rows, not waxy . CHRYSOM YXA. 



UBOMYCES LINK. 



Teleutospores one-celled, brown, produced singly on per- 

 manent pedicels, usually longer than the spore, arising from a 

 compact layer of small irregularly shaped cells beneath the epi- 

 dermis, which is finally ruptured, exposing the more or less 

 powdery mass. 



Like most of the genera of UrcdinecB the biological 

 development of the Vromyces is very complex, and in the dif- 

 ferent species variously diversified. All the spore-forms exist 

 on the same or different hosts, or any one, or even all but one 

 (the teleutospore) may be wanting. In most cases the teleuto- 

 spore germinates only after a considerable period of rest, but 

 in a few species exceptions to this occur, and there are also 

 exceptions in regard to the permanence of the pedicels. When 

 the spores readily fall from the stalks, they can be distin- 

 guished from stalked uredospores by the different appearance 

 usually smooth instead of being roughened with minute and 

 mostly sharp-pointed prominences or by the tardy germina- 

 tion when ripe. Puzzling forms occur, in which some of the 



