152 Bulletin 313 



mass, about 6-10 mm. in length, covered rather permanently by the 

 transparent basal parts of the glumes ; spores lighter-colored on one 

 side, usually subspherical or spherical, smooth 5-9 /x, the most elong- 

 ate rarely 9-11 /a., in length." North American Flora, v. 7, p. 6 

 (1906). 



877. Infected head of barley. 878. Spores, 1/12. 



UsTiLAGO LEVIS (K. & S.) Magn.- — On inflorescence of cultivated 

 oats. ''Sori in spikelets forming a black-brown spore-mass, some- 

 times small and entirely concealed by the glumes but usually evident 

 and destroying and inner basal parts ; spores lighter-colored on one 

 side, subspherical to spherical or rarely more elongate, smooth, 5-9 fx, 

 the most elongate rarely 11 /x, in length." North American Flora, v. 

 7, p. 7 (1906). 



879. Infected head of oats. 880. Spores, 1/12. 



UsTiLAGO NEGLECTA Niessl.- — On the foxtail grass. "Sori in spike- 

 lets infecting all of the spike, ovate, 2-3 mm. in length enclosed by 

 glumes, soon rupturing and disclosing a dusty dark-brown spore- 

 mass ; spores dark brown, usually ovoid to spherical or sometimes 

 more elongate, prominently and abundantly echinulate, chiefly 10-14 

 fi in length." North American Flora, v. 7, p. 16 (1906). 



881. Infected head of foxtail grass. 882. Spores, 1/12. 



UsTiLAGO NUDA (Jens.) K. & S. — On inflorescence of cultivated 

 barley. "Sori in spikelets forming a dusty olive-brown spore-mass, 

 about 6-10 mm. long by half as wide, temporarily protected by a thin 

 membrane but soon becoming dissipated and leaving the naked rachis 

 behind; spores lighter-colored on one side, minutely echinulate, sub- 

 spherical to spherical or occasionally mora elongate, 5-9 fi in length." 

 North American Flora, v. 7, p. 8 (1906). 



883. Infected head of barley. 884. Spores, 1/12. 



UsTiLAGO PERENNANS Rostr. — On infloresccncc and leaves of 

 Arrhenatherum elatius. "Sori in spikelets, forming a black-brown 

 adhering spore-mass, sometimes small and entirely concealed by the 

 glumes but usually evident and destroying inner and basal parts : 

 spores lighter-colored on one side, spores subspherical to spherical or 

 rarely more elongate, smooth, 5-9 /x, the most elongate rarely 11 /i in 

 length." North American Flora, v. 7, p. 7 (1906). 



885. Healthy head of A. elatius. 886. Infected head. SS7. Spores, 1/12. 



