﻿2t>8 
  INTRODUCTION 
  TO 
  BOTANY 
  

  

  It 
  may 
  grow 
  about 
  the 
  edge 
  of 
  the 
  water 
  or 
  upon 
  extremely 
  

   wet 
  soil 
  that 
  has 
  been 
  formed 
  by 
  the 
  partial 
  decay 
  of 
  plants. 
  

   On 
  account 
  of 
  the 
  peculiar 
  structure 
  of 
  the 
  leaves 
  these 
  plants 
  

   hold 
  water 
  in 
  great 
  quantities. 
  The 
  leafy 
  shoot 
  of 
  Sphagnum 
  

   continues 
  its 
  growth 
  at 
  the 
  tip 
  from 
  year 
  to 
  year, 
  while 
  tin- 
  

   older 
  submerged 
  portions 
  gradually 
  become 
  partially 
  decayed 
  

   and 
  intermingled 
  with 
  other 
  plant 
  material. 
  A 
  semi-solid 
  sur- 
  

   face 
  of 
  soil 
  is 
  gradually 
  formed, 
  and 
  this 
  often 
  supports 
  many 
  

   kinds 
  of 
  plants 
  beside 
  ,S////^ 
  /"'"" 
  After 
  long 
  periods 
  of 
  aeeii- 
  

   imilat 
  ion 
  the 
  partially 
  decayed 
  material 
  becomes 
  compressed 
  by 
  

   the 
  increasing 
  weight 
  above 
  it 
  and 
  is 
  known 
  as 
  peat. 
  When 
  

   removed 
  and 
  dried 
  (sometimes 
  compressed 
  into 
  bricks), 
  it 
  is 
  

   used 
  as 
  fuel 
  and 
  rinds 
  a 
  market 
  in 
  many 
  parts 
  of 
  the 
  world. 
  

   Xj>/i<i</tiinn 
  is 
  quite 
  commonly 
  used 
  as 
  a 
  packing 
  material 
  and 
  

   also 
  for 
  holding 
  moisture 
  about 
  potted 
  plants. 
  

  

  254. 
  General 
  characteristics 
  of 
  the 
  liverworts. 
  These 
  pecul- 
  

   iar 
  plants 
  (tig. 
  20<>) 
  take 
  their 
  name 
  from 
  their 
  supposed 
  

   resemblance 
  to 
  the 
  human 
  liver. 
  Most 
  of 
  them 
  grow 
  in 
  moist, 
  

   well-shaded 
  regions, 
  though 
  sometimes 
  they 
  are 
  quite 
  exposed 
  

   and 
  in 
  a 
  few 
  cases 
  they 
  may 
  even 
  grow 
  in 
  intense 
  light 
  and 
  

   heat. 
  Few 
  of 
  them 
  look 
  much 
  like 
  mosses, 
  but 
  some 
  have 
  

   leaf-like 
  structures 
  which 
  quite 
  closely 
  resemble 
  them. 
  

  

  The 
  most 
  commonly 
  found 
  liverworts 
  lie 
  flat 
  upon 
  the 
  

   ground 
  or 
  upon 
  whatever 
  supports 
  them. 
  From 
  the 
  under- 
  

   surface 
  many 
  rhi/,oids 
  grow. 
  The 
  plants 
  are 
  usually 
  dark 
  

   green, 
  being 
  abundantly 
  supplied 
  with 
  chlorophyll. 
  They 
  grow 
  

   forward, 
  the 
  lobes 
  continuing 
  to 
  branch 
  until 
  solid 
  mats 
  are 
  

   formed. 
  Older 
  portions 
  of 
  the 
  plant 
  die, 
  leaving 
  the 
  younger 
  

   branches 
  as 
  new 
  and 
  independent 
  plants. 
  

  

  In 
  some 
  liverworts, 
  cups 
  form 
  on 
  the 
  upper 
  surface, 
  and 
  in 
  

   these 
  cups 
  small, 
  flattish, 
  green 
  buds 
  are 
  developed. 
  These 
  

   buds, 
  when 
  they 
  fall 
  from 
  the 
  cups 
  or 
  are 
  removed 
  in 
  some 
  

   other 
  way, 
  may 
  grow 
  into 
  new 
  liverwort 
  plants. 
  Also, 
  in 
  such 
  

   liverworts 
  as 
  those 
  shown 
  on 
  page 
  269, 
  upright 
  stalks 
  grow 
  

   from 
  the 
  prostrate 
  parts 
  of 
  the 
  plants, 
  and 
  in 
  the 
  heads 
  that 
  

   are 
  produced 
  on 
  the 
  ends 
  of 
  these 
  stalks 
  the 
  sex 
  organs 
  are 
  

  

  