UROCYSTIS. 



315 



Urocystis occulta (Wallr.). (Britain and U.S. America.) This 

 species is common on the haulms, leaves, leaf-sheaths, and less 

 commonly on floral parts of Secale cereale (rye). It causes the 



Fig. 172. — Urocystis occulta on Rye. The ears are stunted, and the spore- 

 powder emerges frpm longitudinal fissures in the upper part of the stems, 

 (v. Tubeuf phot.) 



formation of grey stripes, from which a black spore-powder 

 escapes. The haulms become diseased and smutty, thereby 

 preventing development of the ear, which remains stunted and 



