378 



CONIFERS 



Figure 409. — Ripe Cone of 

 Pine. 



But in the fall or during a dry 

 time in summer, the cells formed 

 are much smaller and the walls 

 thicker. These small cells which 

 show most plainly make up the 

 annual ring. During a season 

 in which long, dry periods occur, 

 more than one ring may be made. 

 From the center to the bark ex- 

 tend lines which are made of 

 pith and are known as medul- 

 lary rays. The part of the 

 stem where increase in thick- 

 ness takes place is just under 

 the bark. 

 Branches. — The branches leave the stem almost hori- 

 zontally and nearly in a circle around the trunk of the 



tree. In the pine they 



curve upward, but each 



kind of evergreen has 



its own habit of curva- 

 ture in its branches. 

 Leaves. — The leaves, 



called needles, are long, 



slender, and flattened on 



one side. They grow 



in bundles of two, three, 



four, or five needles, 



according to the kind 



of pine. The leaves, 



which are borne but 



once in a place, remain 



on the tree from two to five years and then fall off, 



leaving the branches bare except near the ends. 



Figure 410. — Other Cones. 

 a, arbor vitae ; b, hemlock. 



