156 I/I/Hii/s Sfdfc Lahoi-iiforij of Natural Hii^fory. 



TIL 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 . Chrysomyxa. 



Uromyoes Link. 



Teleutospores one-celled, brown, produced singly on ])er- 

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

 compact layer of small irregularly shaped cells beneath the epi- 

 dermis, which is finally rui)tured, exposing the more or less 

 powdery mass. 



Like most of the genera of Uredinew the biological 

 development of the I'lvini/ces 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. Li most cases the teleuto- 

 spore germinates only after a considerable period of rest, but 

 in a few si^ecies 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 



