SUCCULENT STEMS 



453 



the older tree. The small twigs of the young tree grow into the 

 hardy branches of the mature tree. The circular rings seen on 

 the cross section of branches and on the stumps of fallen trees 

 show the amount of wood made by the cambium from year 

 to year (Fig. 320). 



Succulent stems. We have only to think of the tender leaves 

 of the sweet pea, of the juicy stem of asparagus, or the stringy 



FIG. 321. Stems used for food. 



but soft stem of the peony, to know that stems are not all 

 woody like those of the grapevine, the lilac bush, and the 

 maple tree. Some plants, like the lilac bush and the maple tree, 



