CHAPTER XXVI 
SEED-BEARING PLANTS (Continued) 
GYMNOSPERMS 
LIFE HISTORY OF THE PINE 
Description of the Tree 
366. The Trunk. Everyone is so familiar with the 
general features of pine trees as to render a detailed de- 
scription unnecessary here. The main stem or trunk is 
normally a straight vertical shaft, that may be traced from 
the ground to the apex of the tree (Fig. 304). Such a 
trunk is called excurrent, in contrast to the opposite type 
which may be traced for only a short distance from the 
ground, to a point where it divides into the main 
branches or limbs. The latter type of trunk is termed 
deliquescent (Fig. 305). 
The excurrent trunk results from the fact that the 
main stem, as well as the lateral branches, always has a 
terminal bud, which carries the trunk upward from year 
to year. Trees may continue to increase in height each 
season, until they have reached the limit for the given 
species. Many factors may, of course, modify the height, 
among which is the limit of height to which the species 
can raise sap. Some species of pine attain a height of 
1 60 feet. 
366. Branching. At first glance pine trees appear to 
bear their main branches in circles or whorls, but closer 
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