An\^Sarm' }         Structure  o f  Epigcza  Repens.  2  3  5 
rays  focus  upon  a  small  area  of  parenchymatous  tissues  included 
between  the  horns  of  the  inner  crescent.  This  parenchyma,  the 
xylem  tissues,  and  the  bast-fibres,  in  the  mature  leaf,  are  all  strongly 
lignified.  Exterior  to  the  crescent-shaped  area  of  bast-fibres  is  a 
region  of  loosely-arranged  parenchyma  enclosing  the  bundle,  except 
on  its  upper  side,  and  extending  nearly  to  the  epidermis  below,  and 
laterally  to  form  the  spongy  parenchyma  of  the  thin  portions  of  the 
lamina.  This  parenchyma  is  quite  similar  in  appearance  to  that 
composing  the  pith  of  the  stem. 
Fig.  3. 
The  epidermis  is  one-layered  and  rather  small-celled,  and  the 
cells  of  the  lower  are  smaller  than  those  of  the  upper  epidermis. 
The  cuticle  is  thinner  than  that  of  most  evergreen  leaves.  The 
rather  compactly-arranged  chlorophyll-bearing  cells  which  face  the 
upper  epidermis  differ  from  most  palisade  tissue  in  being  but 
slightly  lengthened.  There  are  two  or  three  layers  of  these 
cells. 
The  ordinary  epidermal  cells,  in  surface  view,  appear  strongly 
wavy  in  outline,  or  lobed,  and  there  is  little  difference  of  shape 
between  those  of  the  upper  and  those  of  the  lower  face  of  the  leaf. 
Stomata  occur  also  on  both  surfaces,  but  are  more  abundant  on 
the  lower. 
