DIVERSELY SPECIALIZED SPIKELETS 



63 



the fertile floret are often slightly adnate to (grown 

 to) those of the sterile spikelets, making the fascicle 

 somewhat difficult to dissect. It is in such cases as 

 this that the fundamental concept of the structure 

 of a grass spikelet enables one to recognize the 

 spikelet and its parts. So much elaboration for the 

 production of a single grain is very exceptional in 

 grasses, which as a whole tend to the elimination of 

 non-essentials. 



A third grass having spikelets in little fascicles is 

 Nazia (see Fig. 54). This is probably not closely 

 related to ^Egopogon 

 and Hilaria, but is 

 commonly grouped 

 with them because 

 of its fascicles falling 

 entire. This little 

 bur-like fascicle is 

 composed of two 

 spikelets, both usu- 

 ally perfect (some- 

 times with a third reduced one). The minute first 

 glumes are back to back, and the large second glumes, 

 covered with stout hook-like hairs, face outward. 

 Note that the glumes are not folded as in ^gopogon 

 and Hilaria but convex. These spikelets afford an 

 excellent example of spine-like hairs. Hairs are an 

 outgrowth of the epidermis (skin) and have no 

 connection with the fibrous structure of the plant. 

 The "thorns" of the rose furnish a well-known 



Fig. 54. A, bur-like fascicle of Nazia 

 aliena; B, single spikelet; C, floret. 



