﻿388 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  TWO 
  FORMS 
  OF 
  BRANCHES 
  IN 
  CASTILLA 
  

  

  The 
  habits 
  of 
  growth 
  of 
  Castilla 
  under 
  forest 
  conditions, 
  where 
  the 
  

   trees 
  have 
  tall, 
  cylindrical 
  trunks 
  are 
  shown 
  in 
  plate 
  1. 
  In 
  open 
  places 
  

   branches 
  are 
  produced 
  only 
  a 
  few 
  feet 
  from 
  the 
  ground, 
  as 
  in 
  plates 
  2, 
  

   3, 
  and 
  4. 
  The 
  upper 
  figure 
  in 
  plate 
  4 
  shows 
  a 
  young 
  plantation 
  of 
  Cas- 
  

   tilla 
  with 
  all 
  the 
  trees 
  producing 
  the 
  slender 
  horizontal 
  branches 
  that 
  

   mark 
  the 
  juvenile 
  stage 
  of 
  this 
  tree, 
  preceding 
  the 
  production 
  of 
  the 
  

   stout 
  ascending 
  branches 
  that 
  form 
  the 
  permanent 
  framework 
  of 
  the 
  

   tree, 
  as 
  shown 
  in 
  the 
  mature 
  tree 
  in 
  plate 
  2. 
  Two 
  young 
  trees 
  also 
  1 
  

   are 
  shown 
  in 
  plate 
  2, 
  and 
  the 
  mature 
  tree 
  has 
  a 
  new 
  shoot 
  with 
  large 
  

   leaves 
  on 
  long 
  horizontal 
  branches, 
  like 
  the 
  young 
  trees. 
  

  

  The 
  horizontal 
  lateral 
  branches, 
  slender 
  and 
  simple, 
  are 
  the 
  out- 
  

   standing 
  feature 
  of 
  the 
  Castilla 
  tree, 
  since 
  they 
  bear 
  most 
  of 
  the 
  leaves 
  

   and 
  all 
  the 
  flowers 
  and 
  fruits. 
  Yet 
  all 
  the 
  branches 
  of 
  this 
  type 
  are 
  

   temporary 
  and 
  deciduous, 
  being 
  released 
  after 
  two 
  or 
  three 
  seasons 
  by 
  

   a 
  basal 
  socket 
  of 
  abscission. 
  The 
  leaves 
  of 
  the 
  lateral 
  branches 
  are 
  

   oblong, 
  large, 
  and 
  pendent, 
  inserted 
  in 
  two 
  ranks. 
  Lateral 
  branches 
  

   are 
  produced 
  only 
  on 
  new 
  growth, 
  one 
  branch 
  from 
  each 
  stem 
  section 
  

   of 
  the 
  trunk, 
  rising 
  from 
  an 
  axillary 
  bud. 
  The 
  lateral 
  branches 
  re- 
  

   main 
  simple 
  because 
  no 
  leaf 
  buds 
  are 
  produced, 
  only 
  flower 
  buds. 
  

  

  The 
  lower 
  lateral 
  branches 
  often 
  grow 
  several 
  feet 
  long, 
  and 
  are 
  to 
  

   be 
  considered 
  as 
  the 
  most 
  specialized, 
  since 
  even 
  the 
  flower 
  buds 
  are 
  

   suppressed. 
  The 
  basal 
  joint 
  of 
  a 
  lateral 
  branch 
  is 
  notably 
  shorter 
  than 
  

   the 
  others, 
  and 
  the 
  leaf 
  is 
  suppressed. 
  The 
  leaves 
  near 
  the 
  base 
  of 
  a 
  

   lateral 
  branch 
  are 
  not 
  as 
  large 
  as 
  those 
  farther 
  out, 
  and 
  in 
  a 
  few 
  weeks 
  

   may 
  turn 
  yellow 
  and 
  fall 
  off. 
  Leaves 
  of 
  lateral 
  branches 
  are 
  often 
  

   found 
  with 
  one 
  of 
  the 
  auricles 
  distinctly 
  lobed, 
  always 
  on 
  the 
  lower 
  

   side, 
  toward 
  the 
  base 
  of 
  the 
  branch. 
  The 
  upper 
  auricle 
  may 
  be 
  larger 
  

   than 
  the 
  lower, 
  but 
  is 
  never 
  lobed. 
  

  

  The 
  branches 
  of 
  the 
  trunk, 
  those 
  that 
  provide 
  the 
  permanent 
  frame- 
  

   work 
  of 
  the 
  tree, 
  usually 
  develop 
  much 
  later 
  than 
  the 
  lateral 
  branches. 
  

   They 
  do 
  not 
  project 
  horizontally 
  like 
  the 
  lateral 
  branches, 
  but 
  are 
  up- 
  

   right 
  or 
  ascending, 
  and 
  are 
  not 
  self 
  -pruning 
  at 
  the 
  base. 
  They 
  are 
  

   not 
  produced 
  consecutively 
  at 
  each 
  joint 
  of 
  the 
  trunk, 
  as 
  the 
  lateral 
  

   branches 
  are, 
  but 
  are 
  relatively 
  few, 
  and 
  do 
  not 
  arise 
  from 
  the 
  axil 
  of 
  

   a 
  leaf 
  but 
  from 
  an 
  extra-axillary 
  bud 
  at 
  the 
  right 
  or 
  left 
  of 
  a 
  lateral 
  

   branch. 
  The 
  location 
  of 
  the 
  extra-axillary 
  buds 
  is 
  consistent 
  in 
  each 
  

   tree, 
  so 
  that 
  the 
  trees 
  can 
  be 
  distinguished 
  readily 
  as 
  right-handed 
  or 
  

   left-handed 
  with 
  respect 
  to 
  the 
  buds 
  thai- 
  give 
  rise 
  to 
  the 
  permanent 
  

   branches. 
  The 
  leaves 
  of 
  the 
  trunk 
  are 
  not 
  distichous 
  like 
  those 
  of 
  the 
  

   lateral 
  branches, 
  but 
  in 
  several 
  ranks, 
  probably 
  representing 
  a 
  spiral 
  

   of 
  five- 
  thirteenths. 
  Two 
  or 
  three 
  short, 
  leafless 
  joints 
  are 
  formed 
  at 
  the 
  

   base 
  of 
  a 
  permanent 
  branch, 
  instead 
  of 
  the 
  single 
  short 
  joint 
  on 
  a 
  

  

  