﻿EOOTS 
  AND 
  THEIR 
  RELATION 
  TO 
  PLANTS 
  25 
  

  

  the 
  root 
  system. 
  Cut 
  off 
  most 
  of 
  the 
  roots 
  of 
  a 
  tree 
  and 
  it 
  

   will 
  die 
  for 
  lack 
  of 
  water. 
  On 
  the 
  other 
  hand, 
  many 
  (though 
  

   not 
  all) 
  kinds 
  of 
  trees 
  may 
  be 
  cut 
  down 
  nearly 
  level 
  with 
  the 
  

   ground 
  and 
  still 
  survive, 
  the 
  stump 
  throwing 
  up 
  a 
  vigorous 
  

   crop 
  of 
  sprouts, 
  which 
  grow 
  into 
  saplings 
  that 
  eventually 
  

   replace 
  the 
  fallen 
  trunk. 
  

  

  The 
  necessity 
  of 
  roots 
  for 
  anchorage 
  is 
  well 
  shown 
  by 
  figure 
  4. 
  

   In 
  many 
  cases 
  the 
  power 
  of 
  the 
  roots 
  to 
  hold 
  trees 
  upright 
  is 
  

   greatly 
  increased 
  by 
  the 
  formation 
  of 
  buttresses 
  of 
  wood, 
  which 
  

   extend 
  for 
  some 
  distance 
  up 
  the 
  trunk 
  from 
  the 
  origins 
  of 
  the 
  

   larger 
  roots. 
  In 
  some 
  large 
  tropical 
  trees 
  these 
  buttresses 
  

   attain 
  an 
  immense 
  size. 
  

  

  22. 
  Earth 
  roots 
  ; 
  direction 
  and 
  extent 
  of 
  root 
  system. 
  The 
  

   roots 
  of 
  most 
  common 
  flowering 
  plants 
  in 
  temperate 
  regions 
  

   are 
  earth 
  roots; 
  that 
  is, 
  they 
  grow 
  in 
  and 
  through 
  the 
  soil. 
  

   The 
  nature 
  of 
  the 
  soil 
  greatly 
  influences 
  the 
  extent 
  and 
  posi- 
  

   tion 
  of 
  the 
  root 
  system. 
  Sandy 
  soils 
  favor 
  the 
  development 
  

   of 
  an 
  extensive 
  root 
  system, 
  while 
  clay 
  soils 
  do 
  not. 
  If 
  the 
  

   good 
  soil 
  forms 
  only 
  a 
  shallow 
  layer 
  over 
  shale 
  or 
  sterile 
  clay 
  

   (or 
  in 
  the 
  arctic 
  regions 
  over 
  ice), 
  the 
  roots 
  spread 
  out 
  in 
  a 
  

   flat, 
  mat-like 
  fashion. 
  

  

  The 
  smaller 
  rootlets 
  are 
  so 
  woven 
  through 
  the 
  soil 
  that 
  it 
  

   is 
  never 
  possible 
  to 
  unravel 
  the 
  entire 
  root 
  system. 
  The 
  roots 
  

   of 
  a 
  single 
  oat 
  plant, 
  if 
  arranged 
  in 
  a 
  straight 
  line, 
  have 
  been 
  

   found 
  to 
  measure 
  over 
  450 
  feet 
  in 
  length. 
  Desert 
  shrubs 
  

   sometimes 
  send 
  their 
  roots 
  down 
  as 
  much 
  as 
  60 
  feet 
  toward 
  

   the 
  water 
  supply. 
  In 
  parts 
  of 
  California 
  it 
  has 
  been 
  found 
  

   that 
  common 
  farm 
  plants, 
  such 
  as 
  alfalfa 
  and 
  wheat, 
  may 
  have 
  

   roots 
  reaching 
  moist 
  earth 
  at 
  a 
  depth 
  of 
  from 
  13 
  to 
  15 
  feet. 
  

  

  Why 
  is 
  deep 
  plowing 
  between 
  hills 
  of 
  half-grown 
  corn 
  

   likely 
  to 
  injure 
  the 
  crop 
  ? 
  

  

  23. 
  Pull 
  of 
  roots 
  due 
  to 
  shortening. 
  Frequently 
  rootlets 
  or 
  

   the 
  taproots 
  of 
  herbaceous 
  plants 
  shorten 
  after 
  they 
  are 
  fully 
  

   grown. 
  This 
  shortening 
  has 
  a 
  tendency 
  to 
  pull 
  the 
  stem 
  and 
  

   leaves 
  of 
  the 
  plant 
  downward. 
  It 
  is 
  interesting 
  to 
  notice 
  how 
  

   some 
  plants 
  with 
  rosettes 
  of 
  leaves, 
  like 
  chicory, 
  dandelion, 
  

  

  