﻿POLLINATION 
  AND 
  FERTILIZATION 
  

  

  139 
  

  

  3. 
  Flowers 
  with 
  conspicuous 
  perianth, 
  often 
  with 
  odor, 
  

   often 
  with 
  nectar, 
  usually 
  with 
  moist 
  or 
  sticky 
  pollen, 
  with 
  

   knob-like 
  or 
  club-shaped 
  stigmas. 
  

  

  A 
  good 
  example 
  of 
  1 
  is 
  the 
  flower 
  of 
  the 
  peppergrass 
  (Lepid- 
  

   iuni) 
  ; 
  of 
  2, 
  the 
  flowers 
  of 
  the 
  grasses 
  ; 
  of 
  3, 
  the 
  showy 
  garden 
  

   flowers, 
  such 
  as 
  lilies, 
  pinks, 
  and 
  roses. 
  

  

  131. 
  Modes 
  of 
  pollen-carrying. 
  Each 
  of 
  the 
  

   three 
  groups 
  just 
  described 
  corresponds 
  to 
  a 
  

   different 
  mode 
  of 
  transference 
  of 
  pollen 
  from 
  

   anther 
  to 
  stigma. 
  

  

  The 
  flowers 
  of 
  1 
  either 
  themselves 
  carry 
  

   pollen 
  from 
  the 
  stamens 
  to 
  the 
  stigma 
  of 
  the 
  

   same 
  flower 
  (for 
  example, 
  by 
  the 
  curving 
  

   inward 
  of 
  the 
  stamens 
  as 
  the 
  flower 
  matures) 
  

   or 
  have 
  it 
  carried 
  from 
  stamens 
  to 
  pistil 
  within 
  

   the 
  flower 
  by 
  insects 
  which 
  visit 
  the 
  flower, 
  

   usually 
  in 
  search 
  of 
  pollen. 
  Such 
  flowers 
  are 
  

   said 
  to 
  be 
  self-pollinated. 
  

  

  In 
  the 
  flowers 
  of 
  2 
  the 
  pollen 
  is 
  carried, 
  

   preferably 
  from 
  a 
  flower 
  on 
  one 
  plant 
  to 
  a 
  

   flower 
  on 
  another 
  plant, 
  by 
  aid 
  of 
  the 
  wind 
  

   or, 
  in 
  the 
  case 
  of 
  a 
  few 
  aquatic 
  plants, 
  by 
  

   water. 
  Such 
  flowers 
  are 
  said 
  to 
  be 
  wind- 
  

   pollinated 
  or 
  water- 
  pollinated. 
  

  

  In 
  the 
  flowers 
  of 
  3 
  the 
  pollen 
  is 
  carried, 
  

   preferably 
  from 
  a 
  flower 
  on 
  one 
  plant 
  to 
  

   a 
  flower 
  on 
  another 
  plant, 
  usually 
  by 
  in- 
  

   sects 
  that 
  visit 
  the 
  flowers 
  in 
  order 
  to 
  

   secure 
  food. 
  1 
  Such 
  flowers 
  are 
  said 
  to 
  be 
  insect-pollinated. 
  

  

  132. 
  Self-pollination 
  and 
  cross-pollination. 
  There 
  is 
  a 
  very 
  

   great 
  physiological 
  difference 
  between 
  self-pollination 
  (1) 
  and 
  

   cross-pollination 
  (2 
  and 
  3). 
  In 
  self-pollination 
  the 
  male 
  cell 
  

   and 
  the 
  egg 
  nucleus 
  with 
  which 
  it 
  unites 
  originate 
  in 
  the 
  same 
  

   flower 
  ; 
  in 
  cross-pollination 
  they 
  originate 
  in 
  different 
  flowers, 
  

   preferably 
  from 
  flowers 
  borne 
  on. 
  different 
  plants. 
  

  

  1 
  Sometimes 
  the 
  pollen 
  is 
  carried 
  by 
  birds, 
  bats, 
  snails, 
  or 
  other 
  animals. 
  

  

  FIG. 
  121. 
  Pistil 
  of 
  

   timothy, 
  with 
  feath- 
  

   ery 
  stigmas 
  

  

  sti, 
  stigmas. 
  Mag- 
  

   nified 
  about 
  20 
  times 
  

  

  