CHAPTER FIFTEEN 



THE EXTERNAL FEATURES OF STEMS 



On a woody stem, nodes, leaf scars, buds, and lenticels may be 

 seen. The nodes are the places where the leaves arise, and they 

 are usually the most prominent external feature of stems. The 

 arrangement of leaves at the nodes has already been discussed 

 (page 62). In addition to the leaf, the node gives rise to one or 

 more buds, just above the place of leaf attachment, in the so- 

 called axil (Latin : axilla, armpit) of the leaf. The part of a stem 

 between two nodes is called an internode. The leaf scars are 

 markings on the stem where leaves have fallen. At intervals 

 along the stem ring-like markings {hud scars) may be found. 

 These show where a terminal bud was formed at some previous 

 time. The lenticels are small, dot-like elevations scattered over 

 the surfaces of the internodes. 



Buds. Stems and branches produce leaves only once. We 

 are accustomed to speak of deciduous trees clothing themselves 

 with a new set of leaves each spring, as though the branches of the 

 previous year put forth a new set of leaves to replace those lost 

 the preceding autumn. As a matter of fact, when we look at a 

 deciduous tree in winter, we see branches and twigs, all of which 

 have borne leaves and none of which will ever bear leaves again. 

 The possibility of producing new foKage lies in the development 

 of new branches and twigs. This is the function of the buds ; 

 from them the new growth of each year arises (Fig. 65). 



The buds of many tropical plants are like those we see at the 

 tops of the stems of garden vegetables. A bud of this kind con- 

 sists of the stem's growing point and the undeveloped leaves, 

 with no special covering of any kind. These naked buds occur 

 also on the underground stems of some of our herbaceous plants. 

 A simple sort of bud covering, which is common in the tropics, 

 is made by the folding together of the stipules. This type of bud 

 covering may be seen in the tulip tree and the magnolias of tem- 



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