LESSON III 



MODIFICATIONS OF THE SPI RELET 



Taking the generalized spikelet as a beginning, 

 examine Figs. 4 and 8. Note that the glumes and 

 lemmas have nerves or veins (fibro-vascular bundles) 

 running from the base to the apex or nearly to it, 

 one nerve in the middle and an equal number on 

 each side, there being an odd number of nerves in 

 the glumes and lemmas. In the palea there are only- 

 two nerves; none in the middle. The modifications 

 and variations of spikelets will be studied, as nearly 

 as possible, in the order of their increasing com- 

 plexity. No attempt should be made to fix in mind 

 the forms of specialization here enumerated. This 

 lesson is only meant to put one on the lookout. for 

 modifications, so that one may be prepared to recog- 

 nize a given organ under various guises. 



(1) Spikelets differ in size. (Bromus or brome- 

 grass, meadow fescue, and blue-grass are examples.) 



(2) The number of florets may be reduced to one 

 or increased to twenty or more. 



(3) The parts of the spikelet vary in their relative 

 sizes. The glumes may be large and the florets small 

 or the florets large and the glumes small. 



(4) The rachilla joints may be slender or thick, so 

 short that the florets appear to be opposite, or nearly 



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