﻿140 
  Retrograde 
  Varieties 
  

  

  hedgehog-burweed, 
  a 
  stout 
  and 
  common 
  weed 
  

   of 
  the 
  western 
  States. 
  Its 
  latin 
  name 
  is 
  Xan- 
  

   thium 
  canadense 
  or 
  X. 
  commune 
  and 
  the 
  form 
  

   referred 
  to 
  is 
  named 
  by 
  Mr. 
  Cockerell 
  X. 
  Woo- 
  

   toniy 
  in 
  honor 
  of 
  Professor 
  E. 
  O. 
  Wooton 
  who 
  

   described 
  the 
  first 
  collected 
  specimens. 
  

  

  The 
  burs 
  of 
  the 
  common 
  species 
  are 
  densely 
  

   covered 
  with 
  long 
  prickles, 
  which 
  are 
  slightly 
  

   hooked 
  at 
  the 
  apex. 
  In 
  the 
  new 
  form, 
  which 
  is 
  

   similar 
  in 
  all 
  other 
  respects 
  to 
  the 
  common 
  

   cocklebur, 
  the 
  burs 
  are 
  more 
  slender 
  and 
  the 
  

   prickles 
  much 
  less 
  numerous, 
  about 
  25 
  to 
  the 
  

   bur 
  and 
  mostly 
  stouter 
  at 
  the 
  base. 
  It 
  occurs 
  

   abundantly 
  in 
  New 
  Mexico, 
  always 
  growing 
  

   with 
  the 
  common 
  species, 
  and 
  seems 
  to 
  be 
  quite 
  

   constant 
  from 
  seed. 
  Mr. 
  Cockerell 
  kindly 
  sent 
  

   me 
  some 
  burs 
  of 
  both 
  forms, 
  and 
  from 
  these 
  I 
  

   raised 
  in 
  my 
  garden 
  last 
  year 
  a 
  nice 
  lot 
  of 
  the 
  

   common, 
  as 
  well 
  as 
  of 
  the 
  Wootoni 
  plants. 
  

  

  Spineless 
  varieties 
  are 
  recorded 
  for 
  the 
  bas- 
  

   tard-acacia, 
  the 
  holly 
  and 
  the 
  garden 
  goose- 
  

   berry 
  (Ribes 
  Grossularia, 
  or 
  R. 
  Uva-crispa). 
  A 
  

   spineless 
  sport 
  of 
  the 
  prickly 
  Broom 
  (Ulex 
  eu- 
  

   ropceus) 
  has 
  been 
  seen 
  from 
  time 
  to 
  time, 
  but 
  it 
  

   has 
  not 
  been 
  propagated. 
  

  

  Summarizing 
  the 
  foregoing 
  facts, 
  we 
  have 
  ex- 
  

   cellent 
  evidence 
  of 
  varieties 
  being 
  produced 
  

   either 
  by 
  the 
  loss 
  of 
  some 
  marked 
  peculiarity 
  or 
  

   by 
  the 
  acquisition 
  of 
  others 
  that 
  are 
  already 
  

  

  