﻿390 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  TWO 
  PRELIMINARY 
  LEAF 
  FORMS 
  IN 
  CASTILLA 
  

  

  In 
  addition 
  to 
  the 
  leaves 
  of 
  the 
  trunk 
  and 
  those 
  of 
  the 
  lateral 
  

   branches, 
  two 
  other 
  forms 
  of 
  leaves 
  precede 
  those 
  found 
  on 
  mature 
  

   trees. 
  A 
  seedling 
  stage 
  of 
  development 
  may 
  be 
  recognized, 
  and 
  also 
  

   a 
  juvenile 
  stage, 
  between 
  the 
  small 
  seedlings 
  and 
  the 
  stage 
  of 
  form- 
  

   ing 
  lateral 
  branches. 
  A 
  young 
  Castilla 
  tree 
  just 
  beginning 
  to 
  develop 
  

   lateral 
  branches 
  is 
  shown 
  in 
  plate 
  5, 
  with 
  two 
  of 
  the 
  large 
  juvenile 
  

   leaves 
  still 
  in 
  place 
  ; 
  above 
  these 
  large 
  leaves 
  is 
  a 
  much 
  smaller, 
  heart- 
  

   shaped 
  leaf 
  subtending 
  one 
  of 
  the 
  lateral 
  branches. 
  Preceding 
  the 
  

   formation 
  of 
  branches, 
  several 
  joints 
  of 
  the 
  axis 
  produce 
  what 
  may 
  be 
  

   considered 
  as 
  juvenile 
  leaves, 
  with 
  large 
  blades 
  and 
  long 
  petioles 
  

   as 
  their 
  outstanding 
  features. 
  

  

  Usually 
  the 
  petioles 
  of 
  the 
  juvenile 
  leaves 
  are 
  3 
  to 
  5 
  inches 
  long, 
  

   sometimes 
  6 
  to 
  8 
  inches, 
  while 
  leaf 
  blades 
  may 
  be 
  more 
  than 
  20 
  inches 
  

   long 
  and 
  8 
  to 
  10 
  inches 
  wide. 
  Leaves 
  of 
  the 
  juvenile 
  form 
  occur 
  also 
  

   on 
  sprouts 
  from 
  stumps 
  or 
  wounded 
  trees 
  and 
  may 
  be 
  even 
  larger 
  

   than 
  those 
  of 
  seedling 
  trees. 
  Juvenile 
  leaves 
  a 
  foot 
  wide 
  and 
  nearly 
  

   2 
  feet 
  long 
  were 
  found 
  on 
  stump 
  shoots 
  in 
  Panama 
  June 
  1923, 
  much 
  

   exceeding 
  the 
  largest 
  leaves 
  on 
  lateral 
  branches 
  of 
  Castilla 
  panamensis, 
  

   even 
  where 
  growth 
  is 
  luxuriant. 
  

  

  The 
  transition 
  from 
  the 
  large, 
  long-stalked 
  juvenile 
  leaves 
  to 
  the 
  

   leaves 
  that 
  subtend 
  the 
  lower 
  branches 
  may 
  be 
  gradual, 
  but 
  often 
  is 
  

   remarkably 
  abrupt, 
  with 
  leaf 
  blades 
  smaller 
  and 
  petioles 
  shorter. 
  The 
  

   normal 
  leaves 
  of 
  the 
  trunk 
  and 
  permanent 
  branches 
  in 
  Castilla 
  elastica 
  

   have 
  petioles 
  about 
  2 
  inches 
  long, 
  with 
  the 
  blades 
  6 
  to 
  7 
  inches 
  long 
  

   and 
  5 
  to 
  6 
  inches 
  wide. 
  The 
  leaves 
  of 
  the 
  lateral 
  branches 
  in 
  vigorous 
  

   young 
  trees 
  may 
  attain 
  a 
  length 
  of 
  15 
  to 
  20 
  inches 
  and 
  a 
  breadth 
  of 
  

   6 
  to 
  7 
  inches, 
  but 
  with 
  petioles 
  only 
  1 
  inch 
  long, 
  often 
  equaled 
  or 
  ex- 
  

   ceeded 
  by 
  the 
  broadly 
  rounded 
  basal 
  auricles. 
  

  

  Preceding 
  the 
  large 
  juvenile 
  leaves 
  are 
  the 
  small, 
  short-petioled 
  

   leaves 
  of 
  the 
  seedling 
  stage, 
  only 
  2 
  or 
  3 
  inches 
  long, 
  as 
  shown 
  in 
  plate 
  

   6. 
  The 
  first 
  two 
  leaves 
  of 
  the 
  seedling, 
  shorter 
  and 
  broader 
  than 
  the 
  

   others, 
  and 
  nearly 
  opposite, 
  may 
  be 
  mistaken 
  for 
  cotyledons. 
  They 
  are 
  

   borne 
  on 
  a 
  long 
  stem 
  section 
  or 
  epicotyl, 
  while 
  the 
  true 
  cotyledons 
  

   remain 
  in 
  the 
  ground, 
  no 
  hypocotyl 
  being 
  formed. 
  The 
  paired 
  basal 
  

   leaves, 
  borne 
  on 
  a 
  long 
  stem 
  section 
  or 
  epicotyl, 
  are 
  broadly 
  cordate 
  

   and 
  open-veined, 
  in 
  contrast 
  with 
  the 
  alternate, 
  oblong, 
  close-veined 
  

   leaves 
  that 
  follow, 
  between 
  the 
  epicotyl 
  leaves 
  and 
  the 
  enlarged 
  juve- 
  

   nile 
  leaves. 
  Thus 
  the 
  foliage 
  of 
  the 
  Castilla 
  tree 
  may 
  be 
  considered 
  as 
  

   a 
  series 
  of 
  specialized 
  leaf 
  forms: 
  cotyledons, 
  basal 
  leaves 
  or 
  epicoty- 
  

   ledons, 
  seedling 
  leaves, 
  juvenile 
  leaves, 
  trunk 
  leaves, 
  and 
  branch 
  leaves. 
  

   Castilla 
  thrives 
  in 
  southern 
  Florida 
  and 
  is 
  worthy 
  of 
  study 
  from 
  the 
  

   standpoint 
  of 
  structural 
  specialization, 
  apart 
  from 
  its 
  economic 
  

   interest. 
  

  

  