﻿204 
  Stork: 
  Studies 
  in 
  the 
  genus 
  Taraxacum 
  

  

  arise 
  there 
  would 
  be 
  no 
  difficulty 
  of 
  its 
  maintaining 
  itself 
  as 
  a 
  

   definite 
  line, 
  since 
  hybridization 
  does 
  not 
  enter 
  as 
  a 
  disturbing 
  

   factor. 
  ^ 
  At 
  the 
  beginning 
  of 
  this 
  work, 
  it 
  was 
  conjectured 
  that 
  

   possibly 
  some 
  of 
  the 
  various 
  forms 
  of 
  our 
  common 
  dandelion 
  were 
  

   fLxed 
  and 
  that 
  they 
  would 
  come 
  true 
  to 
  type 
  in 
  the 
  following 
  gen- 
  

  

  A 
  . 
  _ 
  ^ 
  * 
  

  

  eration. 
  While 
  

  

  find 
  anywhere 
  in 
  the 
  literature 
  an 
  explanation 
  of 
  the 
  true 
  nature 
  

   of 
  these 
  various 
  forms 
  of 
  T. 
  vulgare 
  and 
  T. 
  erythrospermum. 
  The 
  

   polymorphous 
  condition 
  has 
  often 
  been 
  noted 
  but 
  definite 
  expla- 
  

   nations 
  are 
  wanting. 
  For 
  example, 
  Sturtevant 
  has 
  deposited 
  in 
  

   the 
  Cornell 
  University 
  Herbarium 
  eight 
  collections 
  of 
  Taraxacum 
  

   vulgare, 
  which 
  he 
  puts 
  into 
  five 
  different 
  varieties, 
  differing 
  from 
  

   one 
  another 
  through 
  a 
  wide 
  range 
  of 
  characters. 
  Are 
  such 
  as 
  

   these 
  to 
  be 
  considered 
  as 
  fixed 
  varieties, 
  are 
  they 
  to 
  be 
  considered 
  

   as 
  variations 
  called 
  forth 
  only 
  for 
  the 
  immediate 
  generation 
  by 
  

   environmental 
  conditions, 
  or 
  are 
  they 
  fluctuating 
  variations 
  that 
  

   Jiave 
  their 
  cause 
  within 
  the 
  plant 
  rather 
  than 
  in 
  the 
  conditions 
  

   of 
  its 
  environment? 
  More 
  than 
  that, 
  since 
  the 
  two 
  species 
  seem 
  

   in 
  their 
  variations 
  to 
  intergrade 
  so 
  that 
  It 
  is 
  at 
  times 
  difficult 
  to 
  

   say 
  whether 
  a 
  particular 
  form 
  belongs 
  to 
  the 
  one 
  species 
  or 
  to 
  

   the 
  other, 
  is 
  T. 
  erythrospermum 
  perhaps 
  to 
  be 
  considered 
  merely 
  

   as 
  one 
  of 
  the 
  numerous 
  forms, 
  a 
  little 
  more 
  distinct 
  than 
  others, 
  

   of 
  T. 
  vulgare? 
  

  

  To 
  help 
  toward 
  a 
  solution 
  of 
  these 
  questions, 
  cultures 
  of 
  the 
  

   plants 
  were 
  resorted 
  to. 
  Dahlstedt 
  (2) 
  has 
  already 
  called 
  atten- 
  

   tion 
  to 
  the 
  necessity 
  of 
  cultures 
  in 
  the 
  study 
  of 
  species 
  of 
  the 
  genus 
  

   and 
  describes 
  seven 
  new 
  species 
  on 
  the 
  basis 
  of 
  cultures 
  carried 
  on 
  

   in 
  the 
  " 
  Berglanischen 
  Garten" 
  at 
  Stockholm. 
  In 
  the 
  summer 
  

   of 
  1916 
  eight 
  plants, 
  determined 
  by 
  the 
  writer 
  as 
  T. 
  vulgare, 
  

  

  were 
  collected. 
  

  

  types 
  of 
  the 
  most 
  

  

  forms 
  commonly 
  observed 
  and 
  were 
  selected 
  with 
  a 
  view 
  toward 
  

   getting 
  the 
  greatest 
  possible 
  differences 
  in 
  leaf 
  characters, 
  size, 
  

   involucral 
  characters, 
  etc. 
  One 
  typical 
  plant 
  of 
  T. 
  erythro- 
  

   spermum 
  was 
  also 
  included 
  as 
  No. 
  9 
  of 
  the 
  series. 
  From 
  each 
  plant 
  

   one 
  well-matured 
  head 
  was 
  selected 
  and 
  the 
  seeds 
  of 
  this 
  preserved 
  

   until 
  February, 
  191 
  7, 
  when 
  they 
  were 
  sown 
  in 
  pans 
  of 
  sterile 
  

   earth 
  in 
  the 
  greenhouse. 
  In 
  April 
  fifty 
  plants 
  from 
  each 
  of 
  the 
  

   nine 
  types 
  were 
  planted 
  In 
  rows 
  in 
  rich 
  garden 
  loam. 
  In 
  spite 
  of 
  

  

  