﻿292 
  

  

  INTRODUCTION 
  To 
  I'-oTANV 
  

  

  277. 
  Seed 
  formation. 
  The 
  oospore 
  that 
  is 
  formed 
  by 
  the 
  

  

  union 
  of 
  tin- 
  sperm 
  and 
  the 
  egg 
  grows 
  and 
  becomes 
  tin- 
  em- 
  

   bryo 
  of 
  a 
  new 
  pine 
  plant. 
  The 
  tissues 
  that 
  surround 
  this 
  

   developing 
  embryo 
  arc 
  partly 
  absorbed 
  by 
  it 
  and 
  used 
  in 
  

   nourishing 
  it. 
  By 
  the 
  time 
  l 
  he 
  embryo 
  has 
  developed 
  root 
  ti;>, 
  

   stem 
  tip, 
  and 
  young 
  leaves, 
  the 
  walls 
  of 
  the 
  ovule 
  have 
  begun 
  

   to 
  harden, 
  and 
  the 
  whole 
  structure 
  is 
  recognized 
  as 
  the 
  seed 
  

   (fig. 
  22<>). 
  When 
  the 
  pine 
  cone 
  opens, 
  usually 
  two 
  years 
  or 
  

   more 
  from 
  the 
  time 
  when 
  pollination 
  occurred, 
  the 
  seeds 
  fall 
  

   to 
  the 
  ground 
  and, 
  if 
  conditions 
  are 
  favorable, 
  begin 
  to 
  ger- 
  

   minate. 
  In 
  germination 
  the 
  embryo 
  

   swells 
  and 
  bursts 
  the 
  seed 
  coat, 
  the 
  

   root 
  grows 
  downward 
  into 
  the 
  soil, 
  

   and 
  the 
  leaves 
  rise 
  into 
  the 
  air; 
  in 
  

   time 
  the 
  embrvo 
  becomes 
  a 
  new 
  tree, 
  

   FIG. 
  226. 
  Diauramof 
  the 
  seed 
  which 
  may 
  bear 
  cones 
  and 
  repeat 
  

  

  the 
  process 
  of 
  reproduction. 
  

  

  The 
  cones 
  may 
  not 
  shed 
  their 
  

   seeds 
  for 
  several 
  years 
  (as 
  in 
  the 
  

   case 
  of 
  the 
  lodgepole 
  pine 
  of 
  the 
  

   Ikoeky 
  .Mountains), 
  or 
  not 
  even 
  

   until 
  the 
  death 
  of 
  the 
  tree, 
  and 
  the 
  

   young 
  plants 
  within 
  the 
  seeds 
  may 
  still 
  remain 
  alive 
  and 
  ready 
  

   to 
  grow 
  when 
  properly 
  placed 
  1'or 
  germination. 
  It 
  is 
  becom- 
  

   ing 
  a 
  common 
  practice 
  of 
  forestry 
  to 
  collect 
  pine 
  seeds 
  in 
  great 
  

   quantities 
  and 
  sow 
  them 
  over 
  thousands 
  of 
  acres, 
  thus 
  resetting 
  

   or 
  extending 
  the 
  areas 
  ill 
  which 
  pine 
  seedlings 
  gro\\ 
  . 
  

  

  278. 
  Other 
  gymnosperms. 
  There 
  are 
  several 
  groups 
  of 
  gym- 
  

   nosperms, 
  but 
  the 
  one 
  to 
  which 
  the 
  pines 
  belong 
  (the 
  conifers 
  ) 
  

   is 
  the 
  only 
  one 
  that 
  need 
  be 
  mentioned 
  here. 
  The 
  conifers 
  take 
  

   their 
  name 
  from 
  the 
  cone-bearing 
  habit 
  which 
  is 
  characteristic 
  

   of 
  all 
  members 
  of 
  the 
  group. 
  In 
  addition 
  to 
  the 
  widely 
  dis- 
  

   tributed 
  genus 
  (/'inns) 
  already 
  discussed, 
  other 
  important 
  

   representatives 
  of 
  the 
  conifers 
  are 
  the 
  spruces 
  (JPicea), 
  which 
  

   have 
  stubby 
  needle 
  leaves 
  (fig. 
  227, 
  A 
  and 
  7?), 
  close-set 
  branches, 
  

   and 
  pendent 
  cones; 
  the 
  Western 
  hemlock, 
  the 
  Douglas 
  fir 
  

  

  of 
  a 
  pine, 
  showing 
  llir 
  embryo 
  

  

  (new 
  pine 
  plant) 
  inclosed 
  \\ 
  it 
  hin 
  

  

  the 
  fund 
  material 
  

  

  At 
  the 
  riicht 
  tip 
  of 
  this 
  emhryo 
  is 
  

  

  tin.- 
  root, 
  ami 
  at 
  the 
  left 
  are 
  the 
  

  

  seed 
  leaves 
  which 
  inclose 
  the 
  

  

  small 
  stein 
  tip 
  

  

  