﻿T. 
  Holm 
  — 
  Pogonia 
  ophioglossoides. 
  17 
  

  

  possesses 
  a 
  tuberous, 
  underground 
  stem, 
  of 
  which, 
  however, 
  

   only 
  one 
  internode 
  seems 
  to 
  be 
  swollen, 
  from 
  the 
  apex 
  of 
  which 
  

   the 
  aerial 
  stem 
  arises. 
  The 
  tuber 
  is 
  oblong, 
  covered 
  with 
  short 
  

   hairs, 
  and 
  bears 
  only 
  one 
  small, 
  scale-like 
  leaf 
  near 
  the 
  apex, 
  

   from 
  the 
  axil 
  of 
  which 
  a 
  slender 
  stolon 
  develops 
  and 
  grows 
  out 
  

   horizontally. 
  In 
  the 
  dried 
  material 
  of 
  this 
  plant, 
  kindly 
  fur- 
  

   nished 
  to 
  the 
  writer 
  by 
  Mr. 
  Thomas 
  H. 
  Kearney, 
  the 
  stolon 
  

   was 
  unfortunately 
  not 
  completely 
  preserved, 
  the 
  apex 
  being 
  

   broken 
  off. 
  We 
  suppose, 
  however, 
  that 
  the 
  tuber 
  develops 
  at 
  

   the 
  end 
  of 
  the 
  stolon 
  in 
  the 
  same 
  manner 
  as 
  we 
  have 
  observed 
  

   in 
  Medeola, 
  but 
  the 
  tuber 
  of 
  this 
  plant 
  is 
  composed 
  of 
  several 
  

   thickened 
  internodes 
  instead 
  of 
  but 
  one 
  as 
  in 
  P. 
  pendula. 
  

   The 
  other 
  parts 
  of 
  the 
  rhizome, 
  the 
  basal 
  internodes 
  of 
  the 
  

   stem, 
  are 
  vertical, 
  slightly 
  hairy 
  like 
  the 
  stolon 
  and 
  provided 
  

   with 
  a 
  few 
  secondary 
  roots, 
  slender 
  and 
  very 
  hairy. 
  No 
  root- 
  

   shoots 
  were 
  found 
  in 
  this 
  species, 
  and 
  we 
  did 
  not 
  expect 
  to 
  

   find 
  such, 
  since 
  the 
  plant 
  is 
  stoloniferous. 
  As 
  stated 
  by 
  Profes- 
  

   sor 
  Wittrock 
  (1. 
  c.) 
  no 
  stoloniferous 
  plant 
  has, 
  so 
  far, 
  been 
  

   observed 
  to 
  develop 
  root-shoots. 
  It 
  seems 
  now 
  from 
  these 
  

   observations 
  as 
  if 
  P. 
  ophioglossoides 
  and 
  P. 
  divaricata 
  are 
  

   closely 
  related 
  species, 
  that 
  they 
  exhibit 
  morphological 
  charac- 
  

   ters 
  that 
  are 
  very 
  different 
  from 
  those 
  of 
  P. 
  verticillata 
  and 
  

   P. 
  ciffinis 
  on 
  the 
  one 
  side 
  and 
  from 
  P. 
  pendida 
  on 
  the 
  other. 
  

  

  While 
  studying 
  the 
  anatomical 
  structure 
  we 
  noticed 
  a 
  few 
  

   points 
  which 
  may 
  be 
  of 
  some 
  interest 
  for 
  further 
  studies 
  of 
  

   North 
  American 
  Orchidece. 
  The 
  roots 
  in 
  these 
  species 
  are 
  

   Mycorrhizae, 
  and 
  the 
  fungal 
  hyphae 
  were 
  observed 
  in 
  the 
  epi- 
  

   dermis, 
  the 
  hypoderm 
  and 
  in 
  the 
  outer 
  strata 
  of 
  the 
  bark- 
  

   parenchyma. 
  The 
  endodermis 
  is 
  thin-walled, 
  but 
  in 
  P. 
  verticil- 
  

   lata 
  there 
  is 
  constantly 
  one, 
  or 
  very 
  seldom 
  even 
  two, 
  quite 
  

   thick-walled 
  endodermis-cells 
  just 
  outside 
  the 
  leptome. 
  The 
  

   pericambinm 
  is 
  thin-walled 
  and 
  in 
  no 
  instance 
  interrupted 
  by 
  

   the 
  proto-hadrome 
  vessels 
  ; 
  furthermore, 
  the 
  conjunctive 
  tissue 
  

   is 
  quite 
  thick-walled 
  in 
  P. 
  verticillata, 
  but 
  not 
  so 
  in 
  P. 
  ophi- 
  

   oglossoides 
  and 
  P. 
  pendula. 
  The 
  rhizome 
  contains 
  fungal 
  

   hyphae, 
  which 
  are 
  located 
  in 
  the 
  epidermis 
  and 
  outer 
  bark, 
  and 
  

   the 
  epidermis 
  has 
  developed 
  numerous 
  long, 
  unicellular 
  hairs 
  

   of 
  a 
  structure 
  like 
  those 
  of 
  the 
  roots. 
  No 
  stereome 
  is 
  repre- 
  

   sented 
  in 
  the 
  rhizome, 
  and 
  a 
  thin-walled 
  endodermis 
  surrounds 
  

   a 
  circle 
  of 
  mestome-bundles, 
  which 
  are 
  bicollateral, 
  periha- 
  

   dromatic, 
  in 
  P. 
  verticillata 
  : 
  there 
  is, 
  furthermore, 
  a 
  central 
  

   pith 
  of 
  thin-walled 
  cells 
  in 
  P. 
  pendida 
  and 
  P. 
  ophioglossoides, 
  

   but 
  of 
  thick-walled 
  in 
  P. 
  verticillata. 
  The 
  tuber 
  of 
  P. 
  pendula 
  

   has 
  a 
  huge 
  bark 
  and 
  pith, 
  and 
  the 
  very 
  small 
  mestome-bundles 
  

   are 
  arranged 
  in 
  a 
  circle 
  inside 
  a 
  very 
  thin-walled 
  endodermis 
  ; 
  

   the 
  epidermis 
  of 
  the 
  tuber 
  contained 
  hyphae. 
  The 
  aerial 
  stem 
  

   of 
  P. 
  ophioglossoides 
  and 
  P. 
  verticillata 
  is 
  hollow 
  and 
  pos- 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  IX, 
  No. 
  49. 
  — 
  January, 
  1900. 
  

   2 
  

  

  