50 SUNFLOWER. [CH. IV 



nothing corresponding to a root-cap, but it has the 

 essential characteristics of places where new cells are 

 manufactured by division; it in fact possesses the em- 

 bryonic character, or quality of continual youth. 



In a growing plant in which the stem has begun 

 the process of elongation several important points may 

 be noted: 



In the first place the leaves are markedly different 

 in form and texture from the cotyledons. But the most 

 striking point to be noted is one which, by its extreme 

 familiarity, tends to be forgotten, namely, that the stem 

 is divided into alternate regions, (1) which have, and (2) 

 which have not, lateral outgrowths. The places where the 

 leaves spring out are known as nodes (fig. 21), and the 

 alternating leafless regions as internodes. Thus, like the 

 body of a worm or an insect, the plant-body is segmented 

 into a number of definite regions from which the lateral 

 appendages spring. The distinction into nodes and in- 

 ternodes comes out clearly in the growth of a bud, where 

 a certain division of labour is apparent : the nodes, which 

 bear the leaves, do not increase in length ; while the in- 

 ternodes, free from leaves, increase greatly in length. The 

 unfolding of a bud is therefore the simultaneous growth 

 of the internodes, and of the leaves at the nodes. 



There is an important difference between the manner 

 of development of the lateral outgrowths of stems and roots. 

 The secondary roots have their origin deep down in the 

 tissues of the primary root. In the stem the outgrowths 

 arise on the surface. The growing point of the stem will 

 be found to end in a blunt, rounded end, and below this to 



