64 



FIRST BOOK OF GRASSES 



example. However stout they may be, they may 

 readily be broken from the bark without tearing 

 the wood. The thorns of hawthorns, plums, and 

 locusts, on the contrary, however slender, can not be 

 broken off. Being reduced branches, the woody 

 fiber (vascular bundles) extends into them from the 

 skeleton of the plant. 



In all the spikelets figured heretofore the sterile 

 florets when present were above the perfect floret. 



In a group of grasses repre- 

 sented by only three genera 

 in the United States, the 

 spikelets bear a pair of sterile 

 florets below the single per- 

 fect floret and these fall at- 

 tached to the fertile one. In 

 sweet vernal-grass, or An- 

 thoxanthum (Fig. 55) the 

 sterile florets consist of 

 empty lemmas unequally 

 awned from the back and 

 divided above the insertion 

 of the awn. The fertile floret 

 is much smaller, awnless, 

 smooth, and shining. A be- 

 ginner, in dissecting this 

 spikelet, might mistake this fertile floret for the 

 grain and so take the sterile florets for a lemma and a 

 very peculiar palea. Whenever a spikelet or any 

 of its parts seems to present a marked departure 



Fig. 55. A, spikelet of Anthox- 

 anthum odoratum; B, pair of 

 sterile florets below the per- 

 fect floret; C, perfect floret. 



