﻿164 
  

  

  INTRODUCTION 
  TO 
  BOTANY 
  

  

  -------- 
  \-----~-------L 
  

  

  155. 
  Types 
  of 
  seedlings. 
  Seedlings 
  1 
  may 
  be 
  divided 
  into 
  

   two 
  groups, 
  monocotyledonoiLS 
  seedliit'/x 
  and 
  <//<<, 
  /_y/,<, 
  A//, 
  ^/s 
  seed- 
  

   liiti/s. 
  Those 
  of 
  the 
  dicotyledonous 
  group 
  may 
  be 
  further 
  sub- 
  

   divided 
  into 
  plants 
  with 
  underground 
  cotyledons, 
  as 
  the 
  pea 
  and 
  

   the 
  oak, 
  and 
  those 
  with 
  aboveyround 
  (<>////<>/</,/.<. 
  as 
  the 
  nuiple, 
  

   bean, 
  squash, 
  and 
  morning-glory 
  (fig. 
  144). 
  

  

  The 
  monocotyledonous 
  seedling 
  may 
  or 
  may 
  not 
  raise 
  its 
  

   single 
  cotyledon 
  out 
  of 
  the 
  ground 
  after 
  germination. 
  The 
  

  

  onion 
  does 
  so, 
  but 
  the 
  grains 
  do 
  not. 
  In 
  

   all 
  the 
  larger 
  grains 
  (as 
  in 
  corn) 
  the 
  

   fitness 
  of 
  the 
  plumule 
  for 
  piercing 
  hard 
  

   clods 
  or 
  bits 
  of 
  sod 
  is 
  very 
  noticeable 
  

   and 
  frequently 
  serves 
  the 
  plant 
  well 
  in 
  

   breaking 
  its 
  way 
  out 
  of 
  the 
  ground. 
  

  

  Dicotyledonous 
  seedlings 
  with 
  under- 
  

   ground 
  cotyledons, 
  like 
  the 
  pea 
  (fig. 
  14") 
  ), 
  

   are 
  better 
  able 
  to 
  force 
  their 
  way 
  out 
  of 
  

   the 
  ground, 
  if 
  planted 
  deep, 
  than 
  are 
  

   most 
  of 
  those 
  with 
  aboveground 
  cotyle- 
  

   dons, 
  like 
  the 
  bean. 
  Therefore 
  even 
  large 
  

   seeds 
  of 
  the 
  latter 
  type, 
  like 
  those 
  of 
  

   the 
  bean, 
  melon, 
  cucumber, 
  and 
  squash, 
  

   unoiH-n,.,! 
  -,,tyi,.- 
  S 
  1 
  1O11 
  11 
  n 
  <>t 
  be 
  plant 
  ed 
  deep. 
  Very 
  minute 
  

  

  dons; 
  GIL, 
  ground 
  hue; 
  ;-, 
  

  

  root; 
  .system; 
  /, 
  rii.linu-n- 
  Seeds, 
  like 
  tllOSC 
  of 
  the 
  portulaca, 
  pOppY, 
  

  

  tary 
  leaves. 
  < 
  >m- 
  half 
  i.at- 
  all 
  j 
  mogt 
  p 
  ] 
  auts 
  o 
  f 
  t 
  j, 
  e 
  pj,^- 
  f 
  am 
  jl 
  v 
  should 
  

  

  11 
  l"l 
  1 
  S 
  1 
  / 
  ( 
  ' 
  / 
  

  

  be 
  planted 
  on 
  the 
  surface 
  of 
  well-raked, 
  

  

  line 
  earth 
  and 
  then 
  barely 
  covered 
  by 
  sifting 
  over 
  them 
  a 
  

   little 
  of 
  the 
  finest 
  loam 
  or 
  by 
  dragging 
  a 
  trowel 
  or 
  other 
  

   suitable 
  implement 
  lightly 
  back 
  and 
  forth 
  over 
  the 
  bed. 
  

  

  156. 
  What 
  becomes 
  of 
  the 
  cotyledons. 
  In 
  the 
  seeds 
  of 
  many 
  

   monocotyledons, 
  as 
  in 
  the 
  grains 
  and 
  in 
  date 
  seeds, 
  the 
  coty- 
  

   ledon 
  is 
  merely 
  an 
  absorbing 
  organ 
  ; 
  it 
  remains 
  within 
  the 
  seed 
  

   and 
  serves 
  to 
  remove 
  liquefied 
  plant 
  food 
  from 
  the 
  endosperm 
  

   and 
  transfer 
  it 
  to 
  the 
  growing 
  embryo. 
  In 
  such 
  dicotyle- 
  

   donous 
  seeds 
  as 
  those 
  of 
  the 
  pea, 
  horse-chestnut, 
  and 
  buckeye, 
  

  

  1 
  Not 
  considering 
  those 
  of 
  coniferous 
  shrubs 
  and 
  trees. 
  

  

  FIG. 
  145. 
  Pea 
  seedling 
  

  

  cot, 
  the 
  

  

  