SPIKELETS WITH HARDENED FRUITS 75 



modification of sterile branches and branchlets into 

 rough bristles is found in the millets (Chsetochloa), 

 common millet, yellow foxtail, and green foxtail. 

 These branchlets are the " involucre of bristles " 

 referred to in many manuals and descriptions. The 

 spikelets fall from their 

 pedicels, as in Panicum, 

 and the bristles remain 

 on the axis. In most 

 of the species the pani- 

 cles are dense and 

 spike-like, the spikelet- 

 bearing branches fas- 

 cicled ' and very short 

 and the sterile ones, or 

 bristles, long and slen- 

 der. In yellow fox- 

 tail, Chcetochloa lute- 

 scens (Fig. 69), the fas- 

 cicle consists of several 

 branches, only one of 

 them spikelet-bearing, F IG< 69 . A 

 the others transformed 

 into slender bristles. 

 Between the ordinary panicle represented in Fig. 67 

 and the bristly spike-like one of yellow foxtail (Fig. 

 69, B) there is every degree of gradation. 



A further specialization of sterile branches is shown 

 in the sand-burs (Cenchrus). Compare Fig. 70 with 

 Fig. 69, A. . Instead of the nearly simple fascicle of 



fascicle from panicle of 

 Chcetochloa lutescens; B, spike-like 

 panicle of same. 



