20 MORPHOLOGY 



the growth of flowers, fruits, and seeds. It is for this 

 reason that these plants are harvested for our use 

 before they run to flower and seed. If they are 

 allowed' to run to flower and seed, they become unfit 

 for human consumption, their store of food being used 

 up by the plants themselves. 



CHAPTER V 



THE STEM 



The stem is the direct prolongation of the plumule 

 of the embryo, and usually grows 

 upwards above the ground. It 

 ' ^'^^ differs from the root not only 

 in the direction of its growth 

 but also in several other re- 

 spects ; thus it bears leaves on 

 its sides while the root bears no 

 leaves, its growing apex is not 

 covered by a protective tissue 

 or cap like that of a root, and 

 the region of it just behind the 

 growing apex is not provided 

 with hairs as is that of a root. 

 The growing apex of the 

 stem is the continuation of the 

 plumule, and consists (fig. 17) 

 of a central axis covered over 

 and protected by a crowd of 

 young and folded leaves. The 

 .rf, Stem, i^, Outer scale leaves, growing apiccs of both stcms 

 and roots are delicate, and there- 

 fore require protection. In the case of roots the 



Fig-. 17. — Stem with Buds, 

 and Section of Bud 



G, Growing- point, l, Leaves. 



