84 MICROSCOPIC FUNGI. 



sahieii, and externally bears consideraMe resem- 

 blance, except in tbe size and colour of the spores 

 (fig. 119), to another species much more common, 

 and which occurs on the leaves of Poa aquatica and 

 P. Jhiitans. The last-named species forms long 

 parallel sori, extending often for several inches along 

 the leaves of the aquatic grasses just named, giving 

 them a very singular appearance (plate V. figs. 105, 

 106) . The spores are small (fig. 107), not being more 

 than one-fourth the length of the last species, and 

 smooth, whilst those are minutely granulated. 



An interesting species occurs, very rarely, on 

 the stems of such grasses as Aira ccesjoitosa and 

 A. aquatica. The sori are in bands at regular dis- 

 tances apart (plate VI. fig. 120), each band being 

 composed of a number of short parallel sori (fig. 

 121). The spores are not more than one-third of 

 the size of those in Z7. longissima. 



Sedges are also subject to attack from other 

 species of smut; one of these (Z7. oKvacea) appears 

 to convert the seeds into a fine olive-coloured dust 

 (plate VI. fig. 126), which gives to the fruit a similar 

 appearance to that presented by com when attacked 

 by JJstilago segetum. Another species, which also ab- 

 sorbs the seeds, becomes hardened and consohdated 

 more than in any other species, and, though larger 

 than the normal seeds, stiU. retaining their form 

 (figs. 109, 110). This is TJsUlago wrceohrv/m, the 

 spores of which are also figured (fig. 111). 



The beaksedge {Bhyncospora alba) suffers from 



