﻿POLLINATION 
  AND 
  FERTILIZATION 
  

  

  147 
  

  

  spad 
  

  

  spathe 
  

  

  stam 
  

  

  -pist 
  

  

  numbers 
  of 
  gnats 
  or 
  midges 
  are 
  attracted 
  to 
  the 
  flower 
  cluster 
  

   and 
  do 
  not 
  easily 
  find 
  their 
  way 
  out 
  of 
  the 
  chamber 
  in 
  which 
  

   it 
  is 
  inclosed, 
  but 
  when 
  they 
  do 
  escape, 
  carry 
  pollen 
  with 
  them 
  

   to 
  the 
  next 
  jack-in-the-pulpit 
  which 
  they 
  visit, 
  and 
  pollinate 
  

   the 
  flowers 
  there. 
  

  

  The 
  flower 
  cluster 
  

   of 
  the 
  common 
  Euro- 
  

   pean 
  arum 
  l 
  has 
  been 
  

   so 
  much 
  more 
  carefully 
  

   studied 
  than 
  that 
  of 
  

   our 
  related 
  American 
  

   plant, 
  and 
  is 
  so 
  much 
  

   more 
  successful 
  in 
  de- 
  

   taining 
  pollinating 
  in- 
  

   sects, 
  that 
  it 
  is 
  worth- 
  

   while 
  to 
  describe 
  it 
  in 
  

   some 
  detail. 
  The 
  cham- 
  

   ber 
  which 
  surrounds 
  FIG. 
  132. 
  Pitfall 
  flower 
  clusters 
  of 
  the 
  

   the 
  flower 
  cluster 
  ap- 
  European 
  arum 
  

  

  pears 
  to 
  be 
  moderately 
  

   open, 
  and 
  admits 
  the 
  

   free 
  entrance 
  and 
  exit 
  

   of 
  small 
  insects. 
  The 
  

   spadix, 
  or 
  floral 
  axis, 
  

   bears 
  several 
  rows 
  

   of 
  downward-pointing 
  

   bristles 
  (fig. 
  132, 
  .B). 
  

   Small 
  midges 
  are 
  at- 
  

   tracted 
  to 
  the 
  interior 
  of 
  the 
  flower 
  chamber 
  by 
  its 
  peculiar 
  

   ammonia-like 
  smell 
  and 
  by 
  its 
  warmth, 
  which 
  is 
  considerably 
  

   greater 
  than 
  that 
  of 
  the 
  outside 
  air. 
  The 
  midges 
  readily 
  

   crawl 
  down 
  through 
  the 
  palisade 
  hairs, 
  often 
  bringing 
  with 
  

   them 
  pollen 
  with 
  which 
  they 
  have 
  become 
  dusted 
  in 
  other 
  

   arum-flower 
  clusters. 
  As 
  they 
  crawl 
  down 
  the 
  spadix 
  they 
  

   pass 
  over 
  the 
  immature 
  staminate 
  flowers 
  (fig. 
  132, 
  ) 
  and 
  

  

  1 
  Arum 
  maculatum. 
  

  

  A, 
  exterior 
  view 
  of 
  the 
  flower 
  cluster, 
  about 
  one 
  

   third 
  natural 
  size 
  ; 
  B, 
  the 
  same 
  drawn 
  to 
  a 
  larger 
  

   scale, 
  with 
  part 
  of 
  the 
  covering 
  removed 
  ; 
  O, 
  part 
  

   of 
  B, 
  drawn 
  to 
  still 
  larger 
  scale, 
  with 
  the 
  flowers 
  

   more 
  mature 
  and 
  the 
  hairs 
  (h) 
  withering 
  and 
  al- 
  

   lowing 
  the 
  escape 
  of 
  imprisoned 
  midges 
  ; 
  spad, 
  

   spadix, 
  or 
  floral 
  axis; 
  spathe, 
  the 
  hood 
  covering 
  

   the 
  axis 
  ; 
  h, 
  hairs 
  closing 
  narrowed 
  part 
  of 
  spathe 
  ; 
  

   stam, 
  group 
  of 
  stamiuate 
  flowers 
  (not 
  mature 
  in 
  

  

  B, 
  mature 
  in 
  C) 
  ; 
  pist, 
  group 
  of 
  pistillate 
  flowers 
  

   (just 
  matured 
  in 
  B, 
  pollinated 
  and 
  developing 
  

  

  seeds 
  in 
  C). 
  A 
  and 
  B, 
  after 
  H. 
  Miiller 
  

  

  