126 



BOTANY OF CROP PLANTS 



weakly, (3) panicle widely spreading, (4) panicle with 

 branches weak and drooping. 



The number of spikelets in a panicle varies, an average 

 number being near 75. The rachis is straight or only sHghtly 

 undulating. A single spikelet is borne at the end of a slender 

 pedicel, which varies in length. 



Spikelet and Flower (Fig. 46).^ — The number of flowers in 

 an oat spikelet varies from two to live, rarely it is one. 

 Three, however, is the usual number. In the so-called " single 



^jlerile 3rd flower 



Fig. 46. — Spikelet of panicle oats (Avena sativa). X 2>2. 



oals,'' but one flower, the basal, matures. In "twin oats," 

 two flowers mature. Three kernels occasionally mature. 

 The upper flowers of the spikelet are often staminate or 

 imperfect. If a large number of spikelets bear three kernels, 

 there is usually a reduction in the number of spikelets in the 

 panicle, as well as in the total weight of grain from that 

 panicle. 



The two empty glumes are unequal, and longer than the 

 lemma. The lemma is rounded on the back, acute, and 

 usually bears an awn which is dorsally attached. As a rule, 



