84 MICROSCOPIC FUNGI. 



salveii, and externally bears considerable resem- 

 blance_, except in the size and colour of tbe spores 

 (fig. 119)_, to anotlier species mucli more common, 

 and wliicli occurs on the leaves of Poa aquatica and 

 P. fluifans. 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, oa 

 the stems of such grasses as Aira ccespitosa and 

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

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

 composed of a number of short parallel sori (fig. 

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

 the size of those in U. longissima. 



Sedges are also subject to attack from other 

 species of smut; one of these [JJ. olivacea) 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 corn when attacked 

 by TJstilago segetum. Another species, which also ab- 

 sorbs the seeds, becomes hardened and consolidated 

 more than in any other species, and, though larger 

 than the normal seeds, still retaining their form 

 (figs. 109, 110). This is TJstilago urceoloriirrij the^ 

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



The beaksedge [Uliyncospora alha) sufi*ers from. 



