Parasitic Fung4 of Illinois. 155 



Roman numerals often following the above indicate the stage 

 of development of the fungus; viz. I., aecidium; TL, uredo; 

 111., teleutospore. 



KEY TO THE GENERA OF UREDINE^E. 



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



A. Spores with a permanent pedicel, mostly smooth and 



dark brown. 



1. Spores one-celled UROMYCES. 



2. Spores two-celled, septum horizontal . . . PUCCINI A. 



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



TRIPHRAGMIUM. 



4. Spores three or more celled, septa horizontal. 



PHRAGMIDIUM. 



5. Spores many-celled, septa variously placed. 



RAVENELIA. 



B. 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-border mostly toothed 



or lobed and recurved ^EcimrM. 



b. Peridium hemispherical or bowl shaped, deeply 



immersed ENDOPHYLLUM. 



c. Peridium elongated, usually cylindrical or coni- 



cal, soon split-fringed above RCESTELIA. 



d. Peridium various, bursting irregularly, white, 



on Conif erae PERIDERMIUM. 



2. Sorus without peridium. 



a. Spores produced in vertical chains, without ped- 



icels, usually accompanied with spermogonia. 



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 GYMNOSPORANGIUM. 



