Grasses 169 



Thus the whole mass of bloom may be loose and 

 spreading, like that of the red-top, or it may be 

 narrow and compressed. 



Sometimes the empty glumes end in a long, 

 bristle-like point, called an awn. 



Often the flowering glume is provided with an 

 awn, which may be straight, or curved, or twisted. 



The problem of providing some mode of con- 

 veyance for the seed has been solved by Nature, 

 for various grasses, in ways as various. 



The "hedge-hog" or '* sand-bur" grass, com- 

 mon in alluvial lands, has converted its outer 

 glumes into thorny coverings for the fruit (Fig. 



43)- 



These catch hold of everything and everybody, 



and succeed so well in spreading the species that 

 it has become a most troublesome weed. 



Uncle Sam warns farmers against it, and even 

 the text-book, forgetful of scholastic calm, dubs it 

 vile. 



The squirrel-tail grass long ago bore three-flow- 

 ered spikelets (Fig. 44). But now the side-blossoms 

 of each trio have dwindled away, and the empty 

 glumes below them have undergone a transformation 

 to subserve the general good, and become long bris- 

 tles, which enable the matured fruit to blow away. 



