SPI RELETS WITH HARDENED FRUITS 



77 



In all the seed-bearing spikelets so far examined, 

 the stamens and stigmas project at flowering time, 

 resulting in cross fertilization of the ovules. A few 

 grasses bear cleistogamous (close-fertilized) as well as 

 openly fertilized spikelets. 

 Such spikelets do not 

 open, and there is usually 

 but a single small stamen 

 which empties its pollen 

 directly on the short stig- 

 mas. The grain is larger 

 than that of open-fer- 

 tilized spikelets. Two of 

 our native grasses, form- 

 ing the genus Amphicar- 

 pon, related to Panicum, 

 are remarkable in that 

 they produce large cleistogamous spikelets under- 

 ground from subterranean branches (Fig. 72^. The 

 plants also bear terminal panicles of ordinary and 

 much smaller spikelets, but these seldom perfect 

 seed. 



SUMMARY 



In Panicese, the millet tribe, the spikelets fall 

 entire. They bear one perfect floret with a sterile 

 floret below it. The lemma and palea of the perfect 

 floret are indurate. The sterile lemma resembles the 

 second glume, the two simulating a pair of glumes, 

 while the first glume is small and looks like an addi- 



FiG. 72. Base of plant of Amphi- 

 carpon Purshii. 



