136 



BOTANY OF CROP PLANTS 



types. The rachis is strongly compressed. Opposite each 

 point on the rachis where the spikelets stand, there is a 

 sharply defined horizontal cushion (Fig. 48). This dis- 

 tinguishes the barley rachis from that of wheat and rye. 

 Furthermore, the single joints of the barley rachis are 

 straight, while in wheat and rye they are bent. 



—lemma 



Fig. 49. — A, triplet of spikelets of six-rowed barley (Hordeum vulgare 

 hexastichon) ; note, that there are three fertile spikelets at the rachis joint; 

 B, triplet of spikelets of two-rowed barley (H. distichon); the two lateral 

 spikelets are sterile; C, single spikelet of hooded barley ( H. vulgare tri- 

 furcatum). 



At each joint of the rachis, there are three spikelets, each 

 one-flowered (Figs. 49 and 50). The lateral spikelets of each 

 triplet are sometiines imperfect, as in two-rowed barley. 

 Each spikelet is on a short branch or rachilla, which is pro- 

 duced beyond the flower and appears as a bristle (Fig. 51) 

 lying within the groove of the grain. As in wheat, there is 



