MODIFICATIONS OF THE SP I RELET 23 



toward the rachilla. Taking this as the "front" 

 of a floret, the back (or dorsum) is the back of the 

 lemma. Spikelets with many florets, or those in 

 which the glumes or lemmas are folded on the mid- 

 nerve, are generally laterally compressed; those with a 

 single fertile floret and with convex (rounded) glumes 

 and lemma are generally dorsally compressed. 



(9) Spikelets are sometimes unisexual (of one sex) 

 instead of perfect (having both stamens and pistil). 

 The two kinds, pistillate (the ovule-producing) and 

 staminate (pollen-producing) may be borne on a 

 single plant, as in corn, with pistillate spikelets in the 

 ear and staminate spikelets in the tassel, or in differ- 

 ent plants, as in salt-grass and buffalo-grass. Grasses 

 with staminate and pistillate spikelets on the same 

 plants a,re monoecious (which means dwelling in one 

 house) ; those with staminate and pistillate spikelets 

 on different plants are dioecious (dwelling in two 

 houses). The unisexual spikelets of a single species 

 may be similar in appearance, or they may be very 

 unlike, as in corn. 



(10) Some grasses with perfect spikelets bear in 

 addition staminate spikelets or neuter spikelets (hav- 

 ing neither stamens nor pistils). These additional 

 spikelets may be similar in appearance to the perfect 

 ones or very unlike them. They are borne in the 

 same inflorescence as the perfect spikelets and are 

 usually paired with them. 



(11) The florets of a single spikelet may be of two 

 kinds, perfect and sterile, the sterile being either 



