GENERAL CHARACTERS OF THE ORDER 479 



arranged a series of sessile bracts in two alternate rows. These 

 bracts are termed glumes, and in the axils of all except the two 

 lowermost ones (a a) flowers are produced which on account of 

 their small size are not seen. The glumes a a are termed the 

 empty glumes of the spikelet, the others similar to / are the 

 flowering glumes. Attached to the very minute stalk which 

 each flower possesses is another bract, named the/a/i? or palea 

 seen at /. It lies opposite to the flowering glume, and be- 

 tween it and the latter the flower is enclosed more or less 

 completely. 



The empty glumes are usually two in number, but there is 

 only one in rye-grass, and the spikelet of sweet vernal-grass 

 possesses four. Sometimes they are small and narrow as in rye, 

 or they may be large and completely enfold the rest of the 

 spikelet as in oats. 



The flowering glumes often differ from the empty ones in 

 having ' beards ' or bristle-shaped structures termed aivns. In 

 barley and ' bearded ' wheats the awns are of great length, while 

 in some instances they are merely short points at the tip of the 

 glume. 



Awns are said to be terminal, dorsal, or basal according to 

 whether they arise from the tip, middle of the back, or the base 

 of the glume. 



The number of flowers in each spikelet varies considerably : in 

 some species, as timothy grass and florin, only one is present, in 

 Yorkshire fog two, while in meadow-grasses, fescues, and rye- 

 grasses there are several. 



All our grasses resemble each other in having their flowers in 

 spikelets, the latter, however, do not constitute the whole in- 

 florescence but are only parts of it. In wheat, rye-grass, and 

 barley the spikelets are sessile upon opposite sides of a straight 

 unbranched main axis, the rachis, the total inflorescence being 

 termed a spike ; in reality it is a spike of spikelets. 



In the majority of grasses the rachis is much-branched and' 



