
46 THE GROWTH AND PARTS OF PLANTS 
stems. Perhaps all these plants have formed the habit 
of long stems because they often grow in large, crowded 
masses, and take this means of lifting themselves above 
other plants in search of light and air. 
In the pines, spruces, and larches the main stem 
rises like a great shaft from the ground straight 
through the branches to the 
top. ‘The highest part is the 
end of this straight shaft. 
These trees have many 
branches reaching out in 
graceful curves, but the main 
stem remains distinct. A 
stem which continues or runs 
through to the top is said to 
be excurrent. Have you ever 
been on the top of a mountain 
surrounded by a forest of 
oaks, birches, beeches, pines, 
and larches? You remem- 
ber how the tall, slender pines or larches towered 
above the oaks or beeches. 
How is it with the oak stem? The branches are larger 
i proportion to the main stem, so that the main trunk 1s 
often lost or disappears. Compare the oak tree or pine 
tree which has grown in the open field with those grown 
in the forest. How should you account for the difference ? 

FIG. 75. Conical type of larch. 
