70 



FIRST BOOK OF GRASSES 



sterile floret often adheres to the palea side of the 

 fruit (the mature fertile floret) as a small thin scale, 

 difficult for the beginner to account for unless he 

 understands the structure of the spikelet. 



This type of 

 spikelet is charac- 

 teristic of the large 

 number of grasses 

 forming the millet 

 tribe. In Panicum 

 the inflorescence is 

 an open or con- 

 tracted panicle. In 

 crab-grass, Synthe- 

 risma sanguinalis 

 (Fig. 61) and its 

 relatives, the spike- 

 lets are borne in 

 1 -sided racemes, 

 much like those 

 of Bermuda-grass 

 (Fig. 48). In the 

 crab-grasses the 

 first glume is mi- 

 nute or suppressed, and the second is commonly 

 much shorter than the sterile lemma and the fertile 

 floret. The fertile lemma and its palea are less 

 indurate than those of Panicum and the margin of 

 the lemma is thin in texture and flat instead of being 

 firm and inrolled, as in Panicum. 



FIG. 61. A, two views of spikelet of Synthe- 

 risma sanguinalis; B, fertile floret; C, in- 

 florescence. 



