﻿MOSSES, 
  LIVERWORTS, 
  AND 
  FERNS 
  

  

  271 
  

  

  256. 
  The 
  rootstock 
  of 
  a 
  fern. 
  If 
  the 
  soil 
  is 
  carefully 
  removed 
  

   from 
  the 
  underground 
  part 
  of 
  one 
  of 
  the 
  common 
  ferns, 
  the 
  

   horizontal 
  rootstock 
  (rhizome) 
  appears 
  (fig. 
  208). 
  The 
  lower 
  

   side 
  of 
  the 
  rhizome 
  gives 
  rise 
  to 
  the 
  roots, 
  and 
  the 
  upper 
  side 
  

   bears 
  the 
  leaves. 
  At 
  the 
  tip 
  of 
  the 
  rootstock 
  is 
  the 
  bud, 
  by 
  

   means 
  of 
  which 
  growth 
  is 
  continued 
  from 
  year 
  to 
  year. 
  The 
  

   leaf 
  scars, 
  or 
  the 
  bases 
  of 
  old 
  leaves, 
  

  

  may 
  usually 
  be 
  seen 
  upon 
  the 
  root- 
  

   stock. 
  The 
  terminal 
  bud 
  grows 
  

   forward 
  each 
  year 
  from 
  a 
  fraction 
  

   of 
  an 
  inch 
  in 
  some 
  ferns 
  to 
  several 
  

   inches 
  in 
  others, 
  and 
  at 
  the 
  begin- 
  

   ning 
  of 
  each 
  season 
  it 
  sends 
  up 
  

   one 
  or 
  more 
  new 
  leaves. 
  

  

  The 
  rhizome 
  of 
  the 
  fern 
  (fig. 
  209) 
  

   presents 
  the 
  first 
  really 
  complex 
  

   stem 
  structure 
  that 
  we 
  find 
  as 
  we 
  

   study 
  the 
  groups 
  of 
  plants 
  in 
  the 
  

   order 
  of 
  their 
  increasing 
  complex- 
  

   ity. 
  This 
  is 
  a 
  woody 
  stem 
  com- 
  

   posed 
  of 
  several 
  kinds 
  of 
  stem 
  

   tissues. 
  Some 
  of 
  these 
  tissues 
  are 
  

   heavy-walled 
  and 
  give 
  rigidity 
  to 
  

   the 
  stem. 
  The 
  rhizome 
  is 
  some- 
  

   times 
  stored 
  full 
  of 
  food 
  in 
  the 
  

   form 
  of 
  starch. 
  Some 
  of 
  the 
  tissues 
  

   consist 
  chiefly 
  of 
  rounded, 
  fiber- 
  

   like 
  bundles 
  which 
  extend 
  length- 
  

   wise 
  throughout 
  the 
  stem. 
  These 
  are 
  the 
  fibrovascidar 
  bundles, 
  

   which 
  term 
  simply 
  means 
  " 
  fibrous 
  bundles 
  of 
  vessels." 
  

  

  257. 
  The 
  leaf 
  of 
  a 
  fern. 
  As 
  a 
  fern 
  leaf 
  develops 
  from 
  the 
  

   bud, 
  it 
  unfolds 
  in 
  a 
  very 
  peculiar 
  fashion 
  (fig. 
  211) 
  known 
  

   as 
  drdnate 
  vernation. 
  The 
  coiled 
  or 
  rolled 
  (circinate) 
  tip 
  of 
  

   the 
  leaf 
  is 
  easily 
  seen 
  even 
  in 
  most 
  old 
  fern 
  leaves. 
  Mature 
  

   fern 
  leaves 
  assume 
  so 
  great 
  a 
  variety 
  of 
  forms 
  that 
  it 
  is 
  impos- 
  

   sible 
  to 
  give 
  any 
  description 
  that 
  holds 
  good 
  for 
  many 
  kinds, 
  

  

  rh 
  

  

  FIG. 
  208. 
  The 
  bracken 
  fern 
  

   (Pteris 
  aquilina) 
  

  

  The 
  rootstock 
  (rh) 
  is 
  horizontal 
  

  

  and 
  grows 
  underground 
  ; 
  upon 
  it 
  

  

  are 
  the 
  huds 
  (b) 
  and 
  the 
  upright 
  

  

  leafstalk 
  (st) 
  

  

  