SESSILE SPIKELETS IN TWO-SIDED SPIKES 41 



florescence dealt with in this lesson form the barley 

 tribe, which from the standpoint of man is the' most 

 important group of grasses, if not of all plants, in the 

 world, containing wheat, barley, and rye. 



SUMMARY 



The specialization in spicate inflorescence is chiefly 

 in the rachis and next in the position of the relatively 

 simple spikelets. 



When the glumes are distorted, standing side by 

 side, as often found in species of Elymus, or when 

 one of them is suppressed, we can tell which is which 

 from the fact that the first, or lowermost, floret is 

 always above or on the same side of the spikelet as 

 the first glume. 



REVIEW 



Collect heads of wheat, rye, barley, quack-grass, species of 

 Elymus, LoUum, or squirrel-tail grass (one or more of these will 

 be found anywhere in the United States). Note whether the 

 rachis readily disjoints. If so, separate out a single joint with 

 the spikelets attached. Note where the rachis breaks, at the 

 summit or base of the joint; note the number of spikelets at a 

 joint and the number of florets to a spikelet. Distinguish the 

 individual spikelets and their parts. If the rachis does not dis- 

 joint, cut across the middle of the internodes, taking out a single 

 joint with attached spikelets. Note the number of spikelets to a 

 joint; whether there are one or two to several fertile florets to the 

 spikelet and whether the spikelet is placed flatwise or edgewise 

 to the rachis. 



Note how spikes bearing spikelets with scabrous awns push 

 themselves forward when handled. 



