rachis joints to increase or decrease in thickness near the base of the spike: (b) any tend- 

 ency to increase or decrease in length near the base of the spike. 



8. Figures 10 and 12 also illustrate two views of a spikelet. Remove one spikelet from 

 your sample spike of wheat. (It will be necessary to remove a joint of the rachis with the 

 spikelet in order to have its parts cohere.) How does the width of the spikelet compare with 

 its thickness? 



9. Place a spikelet near the middle of the upper portion of a clean sheet of your note 

 paper. Now dissect the spikelet as illustrated by Fig. 13, p. 36. When you have the dis- 

 sected spikelet properly arranged, write the names beneath the respective parts. Then remove 

 the parts of the spikelet a little to one side and in their place draw figures about natural 

 size. 



10. (a) Draw a view of the wheat kernel* (five diameters) looking down upon the suture. 



Indicate the location of brush, suture, and check, (b) 

 Make a drawing of the wheat kernel (five diameters) 

 looking down upon the germ side. Indicate the loca- 

 tion of germ and brush, (c) Make a neat drawing 

 (five diameters) of the cross section of a wheat kernel 

 cut in two neat the middle. Indicate the location of 

 suture and cheek. (d) Make a neat drawing (five 

 diameters) of the longitudinal section of a wheat ker- 

 nel split along the line of the suture. Indicate brush, 

 cheek and germ. 



* .' 



Fig. 14. Cross section of wheat kernel. 



Fig. 15. Germ side Fig. 16. Suture side H. Observe that surrounding each wheat kernel 



(a) Brush; (b) Cheek; (r) Suture; (d) , ~ . „ 



Germ. (Anderson) are two modified leaves (bracts) technically known as 



glumes, (a) What names are given to these two 



glumes? (I)) Which glume covers the suture side of the kernel? (c) Does the shape of 



this glume indicate in any way that it lies next to the suture? (d) Do the edges of the palea 



fit inside or outside the edges of the flowering glume? (e) Does the palea have an awn or 



awn point? (f) If the wheat is bearded, which glume bears the beard? (g) Which of the 



two glumes is somewhat hyaline, i. e., something like tissue paper? 



12. In field crop work a mature wheat kernel, together with flowering glume and palea, 

 is known as a wheat flower. This idea of a flower will not exactly conform with the tech- 

 nical definition of a flower, but answers our purpose at this place. 



A flowering glume and palea with a wheat kernel enclosed is spoken of as a fertile flower, 

 whereas if the kernel fails to form, it is known as a sterile flower, (a) How many fertile 

 flowers were present in the spikelet which you dissected? (b) How many sterile flowers? (c) 

 How many flowers in all? (d) Examine spikelets in various parts of the head in order to 

 determine whether or not the number of flowers per spikelet is the same throughout the 

 spike, (e) In what part of the spikelet are the sterile flowers usually found? 



The central axis of the spikelet is known as the rachilla (literally a little rachis) and is 

 most evident as a support of the sterile flowers. The rachilla of the spikelet corresponds 

 quite closely with the rachis of the spike. 



13. (a) Is there any variation in the number of outer glumes per spikelet in wheat? (b) 

 Do the outer glumes most resemble the flowering glume or palea? (c) What do you con- 

 sider to be a good definition of a spikelet? 



•The dimensions of the drawing are to be five timet li-ose of the object. 



37 



