306 THE FUNGI WHICH CAUSE PLANT DISEASE 



by Lobelius.i" Persoon in 1801 first gave a definitely recognizable 

 description." In 1888 the species was separated from the other 

 smut on barley.i^ 



The spores germinate freely in water by one, rarely two, tubes, 

 usually 4-celled, and produce abundant sporidia; these increase by 

 budding, produce germ tubes, or fuse with each other. 

 U. levis (K. & S.) Mag.2*' "" 



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, 

 subspherical to spherical or rarely elongate, smooth, 

 6-9 n, the most elongate rarely 11 /i in length. 



On oats throughout America and Europe, prob- 

 ably more common than records show as- it is very 

 difficult to distinguish from U. avenae from which 

 it differs chiefly in its smooth granular spores. 

 IT. macrospora Desm. 



Sori in leaves and glumes, generally showing as 

 linear striae, but often more or less merged, at 

 first covered by the epidermis, but this later rup- 

 turing and disclosing black-brown dusty lines of 

 Fig. 221.— u. le- gpores: spores medium to dark reddish-brown, 



VIS, germina- f. „ . , i • i • n 



tion in modi- chiefly ovoid to sphencal or occasionally some- 

 solution!^ Af- what irregular and elongate, coarsely verrucose, at 

 ter Clinton. circumference usually showing the projections as 

 tinted blunt scale-like appendages, sometimes even semi-reticulate, 

 12-19 n in length. 

 On various species of Agropyron in Europe and America. 

 U. nuda (Jens.) K. & S.^*- "« 



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 which soon becomes dissipated leaving the naked rachis 

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

 subspherical to spherical or occasionally elongate, 5-9 n in length. 

 In Europe and America. This smut on barley is distinguishable 

 from the covered smut, U. hordei, by its olive-green spore-mass 

 and by its early shedding of spores. As a rule, each spikelet, ex- 



