﻿298 
  INTRODUCTION 
  TO 
  BOTANY 
  

  

  thousand 
  species, 
  and 
  some 
  think 
  this 
  number 
  too 
  low. 
  Added 
  

   to 
  this 
  fact 
  of 
  the 
  large 
  number 
  of 
  species 
  is 
  the 
  fact 
  that 
  the 
  

   number 
  of 
  individuals 
  of 
  a 
  species 
  may 
  often 
  be 
  enormous, 
  as 
  

   in 
  the 
  common 
  blue 
  grass, 
  oats, 
  or 
  corn, 
  each 
  species 
  of 
  which 
  

   consists 
  of 
  unknown 
  millions 
  of 
  individual 
  plants. 
  

  

  The 
  diversity 
  of 
  angiosperms 
  in 
  chnniral 
  composition 
  is 
  

   equally 
  great. 
  Some 
  constitute 
  our 
  most 
  important 
  foods, 
  

   others 
  produce 
  a 
  large 
  part 
  of 
  our 
  medicines, 
  and 
  others 
  

   produce 
  substances 
  so 
  poisonous 
  that 
  they 
  are 
  feared 
  by 
  all 
  

   who 
  know 
  about 
  them. 
  

  

  282. 
  Vegetative 
  structures. 
  The 
  essential 
  facts 
  regarding 
  

   the 
  ways 
  in 
  which 
  angiosperms 
  make 
  and 
  use 
  their 
  food 
  mate- 
  

   rial 
  have 
  already 
  been 
  given 
  (Chapter 
  II 
  and 
  the 
  following 
  

   chapters). 
  There 
  have 
  also 
  been 
  abundant 
  discussions 
  to 
  show 
  

   something 
  of 
  the 
  variety 
  of 
  structures 
  that 
  plants 
  of 
  this 
  group 
  

   exhibit 
  when 
  they 
  grow 
  under 
  different 
  circumstances, 
  as 
  in 
  

   the 
  water, 
  on 
  especially 
  dry 
  land, 
  and 
  under 
  extremes 
  of 
  tem- 
  

   perature. 
  The 
  ways 
  in 
  which 
  different 
  vegetative 
  structures 
  

   are 
  used 
  as 
  means 
  of 
  reproduction 
  are 
  presented 
  in 
  chapters 
  

   on 
  roots, 
  stems, 
  leaves, 
  etc. 
  Reproduction 
  by 
  means 
  of 
  flowers 
  

   has 
  also 
  received 
  some 
  attention, 
  but 
  a 
  further 
  discussion 
  at 
  

   this 
  time 
  will 
  serve 
  to 
  connect 
  the 
  angiosperms 
  with 
  the 
  pre- 
  

   ceding 
  groups. 
  

  

  283. 
  The 
  angiosperm 
  flower. 
  The 
  name 
  flower 
  is 
  some- 
  

   times 
  used 
  in 
  speaking 
  of 
  the 
  collections 
  of 
  sporophylls 
  that 
  

   are 
  seen 
  in 
  the 
  cones 
  of 
  pines. 
  In 
  the 
  angiosperms, 
  in 
  addi- 
  

   tion 
  to 
  sporophylls, 
  there 
  are 
  usually 
  other 
  leaf-like 
  organs 
  

   around 
  the 
  sporophylls, 
  and 
  the 
  presence 
  of 
  these 
  additional 
  

   floral 
  leaves 
  is 
  popularly 
  considered 
  as 
  essential 
  to 
  the 
  flower 
  

   (figs. 
  9 
  and 
  102). 
  These 
  added 
  floral 
  leaves 
  are 
  usually 
  colored, 
  

   often 
  in 
  very 
  striking 
  ways. 
  There 
  are 
  angiosperm 
  flowers 
  

   that 
  do 
  not 
  have 
  these 
  added 
  floral 
  leaves, 
  such 
  flowers 
  being 
  

   naked 
  (fig. 
  104). 
  No 
  complete 
  distinction 
  can 
  be 
  made 
  be- 
  

   tween 
  the 
  collection 
  of 
  sporophylls, 
  which 
  in 
  the 
  pines 
  was 
  

   called 
  a 
  strobilus, 
  and 
  the 
  collection 
  which 
  is 
  commonly 
  known 
  

   as 
  a 
  flower 
  in 
  the 
  angiosperms. 
  

  

  