CHAPTER III 

 VEGETATIVE SHOOT— LEAVES 



A SHOOT, in addition to possessing stems and leaves, may bear 

 flowers. If we exclude the flowers, the remainder of the shoot 

 may be spoken of as constituting the vegetative shoot. For 

 the present, flowers will not be considered. 



By making marks in Indian ink at equal distances along the 

 stem, it is easily shown that a stem grows in length only near its 

 tip. We can see this apical growth even more simply by 

 observing the leaves constituting a growing bud. At first they 

 are packed close together, but as the terminal part of the stem 

 elongates they become separated by distinct intervals along the 

 latter (figs. 6-11). Thus the youngest part of a single stem is 

 nearest its tip, and the oldest part is that portion which is 

 nearest its base. 



If we pull the leaves from an actively growing bud of a 

 Wallflower or Sunflower, we see that the external leaves of the 

 bud are inserted lower down the stem than the internal leaves, 

 and are larger than the latter; and the inmost leaves are the 

 smallest, and are inserted nearest the actual end of the stem. 

 Thus leaves arise* only in the region of the apex of a stem and 

 appear in acropetal succession — that is, the youngest leaf is the 

 one which is nearest the end of the stem. As the tip of the 

 stem elongates, the leaves are, so to speak, left behind, and 

 continue to grow till they attain their full size. 



The leaves are attached laterally to the stem at certain 

 points, which are termed nodes. These points of attachment 

 are separated by portions of the stem — the intemodes — which 

 are devoid of leaves but connect the successive nodes (see 

 figs- 4> S)- 



* The leaves arise as external lumps on the side of the stem, and are thus 

 exogenous in origin. 



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