OTHER STEMS 



L >( .)1 



the medullary rays serves as a storehouse for food and 

 as lateral conductors of sap. 



Liquids are always passing along the paths indicated, 

 but this process is observed most readily in the spring 

 when the sap runs from 

 the broken end of a 

 branch. When the 

 leaves are grown, much 

 of the water carried to 

 them is lost by transpira- 

 tion, and little is left to 

 be carried back. In the 

 spring, water is carried 

 down, as well as up. 



Most of our common 

 lumber is made by saw- 

 ing the trunks of trees 

 lengthwise. Sawing in 

 this way shows the 

 annual rings as long lines (Figure 295), but does not show 

 the medullary rays except in a few boards. Lumber t<> be 

 used in furniture is often cut so as to show as many med- 

 ullary rays as possible. The rays are lighter in color and 

 more glistening than the woody layers. 



A tree grows by adding a layer of new wood each year. 

 The branches of the current season have only a single ring 

 of wood, while those of the season bet ore have two rings, 

 and so on. 



LABORATORY STUDY OF TWIGS 



Examine a twig from a horse-chestnul tree, and identify 1 1 the termi- 

 nal buds; (2) lateral buds; (8) leaf scars ; (4) dots in leaf 

 (5) rings; ((>) scales covering buds; (7) breathing pores or lentta 

 Dissect a bud to see what it contains. Make a cross Bection of a stem 



and find (1) the pith ; (2) woody rings; (3) bark in two layers. 



Figure 296. — Food Storage. 

 Creeping stem of Canada ginger. 



