﻿THE 
  STEM 
  AND 
  THE 
  LEAF 
  

  

  61 
  

  

  per 
  year 
  continues 
  to 
  increase, 
  and 
  then 
  diminishes. 
  For 
  ex- 
  

   ample, 
  the 
  long-leaf 
  pine 
  (fig. 
  229) 
  grows 
  only 
  about 
  -| 
  inch 
  

   the 
  first 
  year. 
  For 
  the 
  first 
  fifty 
  years 
  it 
  makes 
  an 
  average 
  

   annual 
  growth 
  of 
  14 
  or 
  15 
  inches 
  ; 
  for 
  the 
  next 
  fifty 
  years, 
  4 
  or 
  

   5 
  inches 
  ; 
  and 
  from 
  one 
  hundred 
  years 
  to 
  extreme 
  old 
  age, 
  

   about 
  1| 
  inches. 
  It 
  usually 
  lives 
  about 
  two 
  hundred 
  years. 
  

  

  FIG. 
  41. 
  An 
  isolated 
  white 
  oak 
  tree 
  destroyed 
  by 
  a 
  violent 
  windstorm 
  

   Photograph 
  by 
  Paul 
  Sargent 
  

  

  The 
  growth 
  of 
  the 
  younger 
  portions 
  of 
  most 
  plants 
  is 
  quite 
  

   unequal, 
  as 
  may 
  be 
  learned 
  from 
  the 
  study 
  of 
  a 
  rapidly 
  growing 
  

   stem, 
  such 
  as 
  the 
  morning-glory. 
  1 
  It 
  will 
  also 
  prove 
  interesting 
  

   to 
  measure 
  such 
  plants 
  as 
  corn, 
  broom 
  corn, 
  hemp, 
  and 
  pole 
  

   beans, 
  to 
  determine 
  whether 
  they 
  elongate 
  more 
  by 
  day 
  or 
  

   by 
  night, 
  and 
  during 
  warm 
  or 
  during 
  cool 
  weather. 
  

  

  1 
  For 
  an 
  illustration 
  of 
  this 
  unequal 
  growth, 
  see 
  Bergen 
  and 
  Davis, 
  

   Principles 
  of 
  Botany, 
  p. 
  17. 
  Ginn 
  and 
  Company, 
  Boston. 
  

  

  