﻿New 
  Species 
  of 
  Oenothera 
  535 
  

  

  The 
  leaves 
  are 
  narrow, 
  and 
  a 
  curious 
  feature 
  

   of 
  this 
  species 
  is 
  the 
  great 
  brittleness 
  of 
  the 
  

   leaves 
  and 
  stems, 
  especially 
  in 
  annual 
  individ- 
  

   uals, 
  especially 
  in 
  those 
  that 
  make 
  their 
  stem 
  

   and 
  flowers 
  in 
  the 
  first 
  year. 
  High 
  turgid- 
  

   ity 
  and 
  weak 
  development 
  of 
  the 
  mechanical 
  

   and 
  supporting 
  tissues 
  are 
  the 
  anatomical 
  cause 
  

   of 
  this 
  deficiency, 
  the 
  bast-fibers 
  showing 
  thin- 
  

   ner 
  walls 
  than 
  those 
  of 
  the 
  parent-type 
  under 
  

   the 
  microscope. 
  Young 
  stems 
  of 
  rubrinervis 
  

   may 
  be 
  broken 
  off 
  by 
  a 
  sharp 
  stroke, 
  and 
  

   show 
  a 
  smooth 
  rupture 
  across 
  all 
  the 
  tissues, 
  

   while 
  those 
  of 
  lamarckiana 
  are 
  very 
  tough 
  and 
  

   strong. 
  

  

  Both 
  the 
  giant 
  and 
  the 
  red-veined 
  species 
  are 
  

   easily 
  recognized 
  in 
  the 
  rosette-stage. 
  Even 
  the 
  

   very 
  young 
  seedlings 
  of 
  the 
  latter 
  are 
  clearly 
  

   differentiated 
  from 
  the 
  lamarckiana, 
  but 
  often 
  

   a 
  dozen 
  leaves 
  are 
  required, 
  before 
  the 
  dif- 
  

   ference 
  may 
  be 
  seen. 
  Under 
  such 
  circumstances 
  

   the 
  young 
  plants 
  must 
  reach 
  an 
  age 
  of 
  

   about 
  two 
  months 
  before 
  it 
  is 
  possible 
  to 
  

   discern 
  their 
  characters, 
  or 
  at 
  least 
  before 
  

   these 
  characters 
  have 
  become 
  reliable 
  enough 
  

   to 
  enable 
  us 
  to 
  judge 
  of 
  each 
  individual 
  

   without 
  doubt. 
  But 
  the 
  divergencies 
  rapidly 
  

   become 
  greater. 
  The 
  leaves 
  of 
  0. 
  gig 
  as 
  are 
  

   broader, 
  of 
  a 
  deeper 
  green, 
  the 
  blade 
  more 
  

   sharply 
  set 
  off 
  against 
  the 
  stalk, 
  all 
  the 
  ro- 
  

  

  