﻿70 
  

  

  INTRODUCTION 
  TO 
  BOTANY 
  

  

  leaves 
  with 
  the 
  veins 
  running 
  somewhat 
  parallel 
  to 
  each 
  other. 
  

   Sometimes, 
  as 
  in 
  the 
  canna 
  (fig. 
  50), 
  the 
  veins 
  run 
  both 
  ways 
  

   from 
  a 
  midrib, 
  but 
  oftener, 
  as 
  in 
  com 
  and 
  the 
  other 
  grasses, 
  

   the 
  veins 
  run 
  from 
  the 
  base 
  to 
  the 
  tip 
  of 
  the 
  leaf. 
  This 
  latter 
  

   system 
  of 
  vein 
  ing 
  is 
  most 
  commonly 
  found 
  in 
  long, 
  narrow 
  

   leaves. 
  Most 
  dicotyledons 
  have 
  net-veined 
  leaves. 
  These 
  

   are 
  of 
  two 
  types: 
  those 
  like 
  the 
  leaf 
  of 
  the 
  willow, 
  oak, 
  and 
  

  

  FIG. 
  50. 
  Parallel-veined 
  

  

  leaf 
  of 
  canna, 
  veins 
  

  

  running 
  from 
  midrib 
  

  

  to 
  margin 
  

  

  FIG. 
  51. 
  An 
  apple 
  twig 
  in 
  the 
  autumn 
  

   Alternate 
  arrangement 
  of 
  leaves 
  

  

  peach, 
  with 
  the 
  smaller 
  veins 
  running 
  both 
  ways 
  from 
  a 
  mid- 
  

   rib; 
  and 
  those 
  like 
  the 
  geranium, 
  hollyhock, 
  and 
  cucumber, 
  

   with 
  the 
  veins 
  radiating 
  from 
  the 
  base 
  of 
  the 
  leaf, 
  like 
  the 
  

   sticks 
  of 
  a 
  fan 
  (fig. 
  49). 
  Net-veined 
  leaves 
  with 
  feather- 
  

   like 
  veining 
  frequently 
  have 
  a 
  length 
  several 
  times 
  as 
  great 
  as 
  

   their 
  width, 
  while 
  those 
  with 
  fan-like 
  veining 
  are 
  often 
  round- 
  

   ish 
  in 
  their 
  general 
  outline. 
  Whatever 
  the 
  shape 
  of 
  the 
  leaf, 
  

   the 
  veining 
  is 
  so 
  disposed 
  that 
  a 
  ready 
  mean* 
  <>t' 
  <//strf/>ufin 
  

   throughout 
  the 
  leaf 
  is 
  offered 
  to 
  the 
  water 
  brouylit 
  into 
  it 
  through 
  

  

  