84 FLOWER-LAND. 



nettle the stem is thickened a good deal at the 

 nodes" (Fig. 33, p. 41). 



It generally is so when several leaves grow out 

 from the stem at the same level, and also when the 

 leaves form a sheath round the stem, as in the pinks 

 and carnations in our gardens. Or you can see these 

 prominently thickened nodes in the stems of the 

 common grass. * Now gather the stems of some 

 herbaceous plants, and a few small branches of trees 

 or shrubs, and point out the nodes to me as we walk 

 along. Yes ! any place where a leaf grows out from 

 a stem is called a node. The parts of the stem 

 between the nodes are called internodes.\ (cf. Figs. 14, 

 p. 1 8 and 44, 45, n the nodes.) 



Leaves are always formed in acropetal succession 

 (p. 79), and unless checked from any cause so they 

 grow. So the youngest leaves upon a stem or branch 

 are those which are nearest to its tip or growing point. 

 Take for instance a simple unbranched stem like that 

 of the dead nettle. As you go upwards from the 

 base of the stem the leaves are younger as you go. 



Now if you notice the position of the leaves upon the 

 stems of the dead nettle, you will see that they do not 

 grow here and there irregularly, but in a certain order. 

 It is so upon other plants : and the different ways 

 in which the leaves are arranged upon the different 



* The stem of a grass is called " a culm" from the Latin 

 " culmus," the stem or straw of corn. 



t From the Latin " inter,' 1 '' between, and " nodus" 



