﻿Smithsonian 
  Report. 
  1943. 
  — 
  Cook 
  

  

  Specialized 
  Leaf 
  Forms 
  in 
  Castilla 
  Rubber 
  Trees. 
  

  

  A 
  young 
  Castilla 
  tree 
  showing 
  three 
  of 
  the 
  specialized 
  leaf 
  forms. 
  The 
  juvenile 
  type 
  is 
  represented 
  by 
  two 
  

   very 
  large, 
  long-stalked 
  leaves; 
  the 
  trunk 
  type 
  by 
  the 
  much 
  shorter 
  and 
  relatively 
  broader 
  leaf 
  subtending 
  

   a 
  branch; 
  the 
  branch 
  type 
  by 
  the 
  short-petioled 
  leaves 
  produced 
  in 
  two 
  ranks 
  along 
  the 
  lateral 
  branches. 
  

  

  