﻿16 
  T. 
  Holm 
  — 
  Pogonia 
  ophioglossoides. 
  

  

  of 
  our 
  Pogonia 
  belongs 
  to 
  the 
  second 
  of 
  these 
  categories, 
  as 
  

   they 
  merely 
  serve 
  as 
  additional 
  means 
  of 
  the 
  vegetative 
  propa- 
  

   gation 
  of 
  this 
  plant. 
  The 
  development 
  of 
  these 
  shoots 
  in 
  

   P. 
  ophioglossoides 
  is 
  interesting 
  and 
  agrees 
  in 
  all 
  respects 
  with 
  

   the 
  observations 
  made 
  by 
  Brim 
  din 
  in 
  Lister 
  a 
  cordata 
  L. 
  The 
  

   most 
  characteristic 
  is 
  that 
  the 
  shoot 
  develops 
  as 
  terminal 
  at 
  the 
  

   end 
  of 
  a 
  root, 
  and 
  that 
  a 
  secondary 
  root 
  pushes 
  out 
  from 
  the 
  

   base 
  of 
  the 
  young 
  shoot 
  and 
  in 
  the 
  same 
  direction 
  as 
  the 
  

   mother-root, 
  as 
  if 
  it 
  was 
  a 
  continuation 
  of 
  this. 
  It 
  is, 
  more- 
  

   over, 
  to 
  be 
  noticed 
  that 
  this 
  secondary 
  root 
  repeats 
  the 
  develop- 
  

   ment 
  of 
  another 
  shoot 
  in 
  exactly 
  the 
  same 
  manner 
  as 
  the 
  first. 
  

   This 
  is 
  readily 
  to 
  be 
  seen 
  in 
  fig. 
  1, 
  where 
  a 
  small 
  shoot 
  is 
  devel- 
  

   oped 
  at 
  S, 
  of 
  which 
  the 
  first 
  secondary 
  root 
  continues 
  the 
  

   direction 
  of 
  the 
  older 
  and 
  bends 
  upwards, 
  terminated 
  by 
  a 
  

   similar 
  growing-point, 
  in 
  which 
  the 
  character 
  of 
  root 
  suddenly 
  

   becomes 
  changed 
  to 
  that 
  of 
  a 
  stem. 
  That 
  these 
  root-shoots 
  are 
  

   not 
  lateral, 
  as 
  it 
  might 
  seem 
  from 
  the 
  first 
  glance, 
  but 
  terminal 
  

   is 
  furthermore 
  explained 
  by 
  the 
  very 
  distinct 
  cross-line, 
  shown 
  

   on 
  our 
  figure, 
  where 
  the 
  root-hairs 
  cease 
  and 
  from 
  where 
  a 
  

   stem-part 
  ( 
  i 
  1 
  ) 
  arises, 
  while 
  the 
  first 
  secondary 
  root 
  (r 
  1 
  ) 
  develops 
  

   from 
  this 
  basal 
  stem-part 
  and 
  grows 
  out 
  horizontally 
  in 
  the 
  

   same 
  direction 
  exactly 
  as 
  the 
  old 
  root 
  (R). 
  The 
  study 
  of 
  the 
  

   growing-point 
  itself 
  shows 
  this 
  development 
  still 
  more 
  plainly. 
  

   The 
  roots 
  of 
  P. 
  ophioglossoides 
  are 
  very 
  slender, 
  and 
  those 
  we 
  

   have 
  described 
  above 
  run 
  immediately 
  in 
  a 
  horizontal 
  direction 
  ; 
  

   most 
  of 
  the 
  other 
  secondary 
  roots, 
  on 
  the 
  contrary, 
  which 
  

   develop 
  higher 
  up 
  on 
  the 
  shoot 
  (r*—r*) 
  9 
  in 
  figs. 
  2 
  and 
  3, 
  grow 
  

   often 
  from 
  the 
  beginning 
  downwards, 
  almost 
  vertically, 
  but 
  

   change 
  their 
  course 
  gradually 
  into 
  the 
  horizontal 
  direction. 
  

   ]N"one 
  of 
  these 
  roots 
  were 
  observed 
  to 
  develop 
  shoots, 
  and 
  their 
  

   function 
  is 
  perhaps 
  to 
  absorb 
  nutritive 
  matters, 
  and 
  to 
  support 
  

   the 
  aerial 
  shoot. 
  The 
  very 
  long, 
  horizontal 
  roots, 
  afford 
  an 
  

   excellent 
  method 
  of 
  distributing 
  the 
  new 
  individuals 
  to 
  a 
  con- 
  

   siderable 
  distance 
  from 
  each 
  other. 
  In 
  regard 
  to 
  P. 
  verticil- 
  

   lata 
  (fig. 
  4) 
  the 
  roots 
  develop 
  similar 
  shoots, 
  but 
  these 
  do 
  not 
  

   appear 
  to 
  be 
  terminal, 
  but 
  lateral; 
  our 
  material, 
  however, 
  was 
  

   too 
  scant 
  to 
  allow 
  any 
  decisive 
  opinion 
  in 
  this 
  respect. 
  

  

  In 
  comparing 
  the 
  rhizome 
  itself 
  of 
  P. 
  ophioglossoides 
  with 
  

   that 
  of 
  P. 
  divaricata, 
  the 
  only 
  variation 
  to 
  be 
  observed 
  is 
  that 
  

   the 
  internodes 
  of 
  the 
  rhizome 
  in 
  the 
  latter 
  are 
  relatively 
  much 
  

   shorter, 
  while 
  the 
  roots 
  show 
  a 
  like 
  external 
  structure. 
  A 
  

   similar 
  very 
  short, 
  but 
  strictly 
  vertical 
  root-stock 
  is,, 
  also, 
  to 
  be 
  

   found 
  in 
  P. 
  verticillata, 
  which, 
  however, 
  differs 
  from 
  all 
  the 
  

   others, 
  only 
  excepting 
  P. 
  ajfinis, 
  in 
  having 
  the 
  aerial 
  leaves 
  

   arranged 
  in 
  a 
  whorl, 
  besides 
  the 
  very 
  striking 
  difference 
  in 
  the 
  

   floral 
  structure. 
  In 
  the 
  last 
  species 
  of 
  Pogonia, 
  P. 
  pendida, 
  

   we 
  notice 
  a 
  rhizome 
  of 
  very 
  singular 
  structure. 
  This 
  species 
  

  

  