Roniiin numerals often following tlic ahovc iudie.ite the stage 

 of development of the funjjjus: vi/. I., u'citliiiiu; FI., iiredo: 

 ill., teleutospore. 



Key to the (tenera of Uredine.e. 



I. Spores at maturity forming a more or less powdery mass. 



A. Spores Avith a permanent pedicel, mostly smooth and 

 dark brown. 



1. Spores one-celled Fkomycks. 



2. Spores two-celled, septum horizoiihil . . . PrcciNiA. 

 B. Spores three-celled, septa in different planes. 



Tkiphragmum. 



4. Spores three or more celled, se])ta horizontal. 



PHRAGMIDrr.M. 



5. Spores many-celled, septa variously placed. 



Raven ELI A. 

 H. Spores with deciduous pedicels or none, one-celled, 

 mostly roughened with minute projections, usually 

 yellow or reddish-brown. 



1. Sorus with a peridium, spores produced in vertical 



chains, without pedicels. 



a. Peridium cup-shaped, rim-l)()rdpr mostly toothed 



or lobed and recurved .EriDHM. 



b. Peridium hemispherical or bowl shaped, deeply 



immersed Endophyllum. 



c. Peridium elongated, usually cylindrical or coni- 



cal, soon split-fringed above Rqistelia. 



d. Peridium various, bursting irregularly, white, 



on Conifene Peridermium. 



2. Sorus without peridium. 



a. Sjjores ju'oduced in vertical chains, without ped- 



icels, usually accompanied with si)ermogonia. 



C.«oma. 



b. Spores produced on pedicels (deciduous), not 



accompanied with spermogonia Uredo. 



II. Spores at maturity embedded in gelatine, two-celled, sep- 



tum horizontal, pedicel long (tymkosporaxoii'm. 



