﻿THE 
  SEED 
  PLANTS 
  

  

  283 
  

  

  soil 
  and 
  supports 
  the 
  heavy 
  stem 
  and 
  branches. 
  The 
  stem 
  is 
  

   generally 
  straight, 
  and 
  the 
  branches 
  usually 
  rise 
  in 
  whorls. 
  

   The 
  lower 
  branches 
  are 
  longest, 
  so 
  that 
  the 
  whole 
  tree 
  pre- 
  

   sents 
  a 
  cone-like 
  outline 
  (fig. 
  219). 
  A 
  heavy 
  bark 
  of 
  a 
  kind 
  

   not 
  seen 
  in 
  any 
  of 
  the 
  

   lower 
  plants 
  covers 
  

   the 
  roots, 
  stem, 
  and 
  

   branches. 
  Leaves 
  are 
  

   borne 
  only 
  on 
  the 
  

   younger 
  branches. 
  The 
  

   small 
  scale 
  leaves 
  are 
  

   inconspicuous, 
  while 
  

   the 
  needle 
  leaves 
  are 
  

   the 
  ones 
  usually 
  ob- 
  

   served. 
  

  

  268. 
  Needle 
  leaves. 
  

   The 
  needle 
  leaves 
  are 
  

   borne 
  in 
  pairs 
  (fig. 
  

   220), 
  in 
  threes, 
  fives, 
  

   etc., 
  the 
  number 
  vary- 
  

   ing 
  with, 
  the 
  different 
  

   species. 
  The 
  number 
  

   of 
  leaves 
  in 
  a 
  cluster 
  

   is 
  one 
  of 
  the 
  distin- 
  

   guishing 
  characteris- 
  

   tics 
  of 
  the 
  species 
  of 
  

   pines 
  ; 
  for 
  example, 
  

   the 
  white 
  pine 
  (Pin 
  its 
  

   ,S'/V/<^* 
  ) 
  has 
  five 
  leaves 
  

   in 
  a 
  cluster, 
  the 
  scrub 
  

   pine 
  (.I'/'nitx 
  if/r,irfi'i>f</ 
  ) 
  and 
  others 
  have 
  two 
  leaves 
  in 
  a 
  cluster, 
  

   the 
  Georgia 
  long-leaf 
  pine 
  (Pinus 
  palustris*) 
  has 
  three, 
  and 
  others 
  

   have 
  a 
  variable 
  number 
  (from 
  two 
  to 
  five) 
  in 
  each 
  cluster. 
  

  

  If 
  one 
  of 
  the 
  clusters 
  of 
  needle 
  leaves 
  is 
  pulled 
  away 
  from 
  

   the 
  branch 
  that 
  bears 
  it, 
  and 
  its 
  basal 
  scale 
  leaves 
  are 
  removed, 
  

   there 
  will 
  be 
  seen 
  a 
  very 
  small 
  white 
  branch 
  upon 
  which 
  the 
  

  

  Flu. 
  219. 
  A 
  white 
  pine 
  (Pinus 
  Strobus) 
  

  

  The 
  .stem 
  is 
  almost 
  straight, 
  the 
  branches 
  stand 
  

  

  approximately 
  at 
  right 
  angles 
  to 
  the 
  stem, 
  and 
  

  

  tin- 
  top 
  is 
  irregularly 
  conical 
  

  

  