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  INTRODUCTION 
  TO 
  BOTANY 
  

  

  which 
  many 
  asexual 
  spores 
  are 
  formed. 
  In 
  both 
  reproductive 
  

   and 
  nutritive 
  work 
  the 
  bryophytes 
  are 
  much 
  more 
  complex 
  

   than 
  the 
  thallophytes. 
  

  

  The 
  ferns 
  have 
  woody 
  tissue 
  and 
  often 
  have 
  immense 
  leaves 
  

   and 
  are 
  well 
  equipped 
  to 
  do 
  chlorophyll 
  work. 
  They 
  often 
  

   store 
  in 
  one 
  year 
  food 
  which 
  serves 
  in 
  part 
  for 
  the 
  growth 
  of 
  

   the 
  next 
  year. 
  Asexual 
  spores 
  are 
  formed 
  in 
  great 
  numbers 
  

   by 
  means 
  of 
  highly 
  specialized 
  sporangia. 
  These 
  spores, 
  when 
  

   they 
  germinate 
  (as 
  in 
  the 
  case 
  of 
  the 
  ferns 
  studied), 
  produce 
  

   chlorophyll-bearing, 
  independent 
  plants, 
  which 
  grow 
  in 
  obscure 
  

   places 
  and 
  produce 
  sex 
  organs 
  by 
  means 
  of 
  which 
  sex 
  spores 
  

   are 
  formed. 
  From 
  the 
  oospores 
  new 
  leafy 
  fern 
  plants 
  grow. 
  

  

  In 
  the 
  spermatophytes 
  we 
  have 
  the 
  most 
  important 
  and 
  

   most 
  prominent 
  plants 
  of 
  the 
  earth. 
  They 
  have 
  vegetative 
  

   structures 
  that 
  are 
  very 
  much 
  more 
  complex 
  than 
  are 
  those 
  

   of 
  any 
  of 
  the 
  preceding 
  groups. 
  These 
  vegetative 
  structures 
  

   are 
  so 
  widely 
  differentiated 
  as 
  to 
  meet 
  the 
  demands 
  of 
  almost 
  

   any 
  conditions. 
  The 
  flower 
  and 
  the 
  seed 
  are 
  special 
  reproduc- 
  

   tive 
  structures 
  which, 
  with 
  successful 
  vegetative 
  structures, 
  

   seem 
  to 
  have 
  given 
  these 
  plants 
  their 
  position 
  of 
  ascendancy 
  

   in 
  modern 
  plant 
  life. 
  

  

  291. 
  Classification. 
  Throughout 
  this 
  book 
  many 
  illustra- 
  

   tions 
  of 
  the 
  seed-plant 
  group 
  of 
  the 
  plant 
  kingdom 
  have 
  been 
  

   used. 
  Although 
  but 
  a 
  few 
  of 
  these 
  illustrations 
  are 
  cited 
  

   here, 
  enough 
  are 
  given 
  to 
  enable 
  the 
  student 
  to 
  relate 
  the 
  

   classification 
  of 
  spermatophytes 
  to 
  that 
  of 
  preceding 
  groups. 
  

  

  GROUP 
  1). 
  Sl'KRMATOPIIYTKS 
  

  

  CLASS 
  I. 
  (JvMNosi-KiiMs. 
  Generalised 
  as 
  illustrations 
  Finns 
  (pine), 
  

  

  Picea 
  (spruce), 
  Jnniperus 
  (juniper), 
  Sequoia 
  ("big 
  trees" 
  and 
  

  

  redwoods) 
  

   CLASS 
  II. 
  ANCIOSPKRMS 
  

  

  Srn-ci.Ass 
  I. 
  MONOCOTYLKDONS. 
  ( 
  !<'iicr;i 
  used 
  as 
  illustrations 
  - 
  

  

  l/ilhuii 
  (lily), 
  Zca 
  (corn), 
  Triticnm 
  (wheat), 
  Arena 
  (oats), 
  and 
  

  

  many 
  others 
  

   SUB-CLASS 
  II. 
  DICOTYLEDONS. 
  Genera 
  used 
  as 
  illustrations 
  

  

  Quercun 
  (oak), 
  Capsella 
  (shepherd's-purse), 
  Pyrus 
  (apple 
  and 
  

  

  pear), 
  Rosa 
  (rose), 
  and 
  many 
  others 
  

  

  