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  INTRODUCTION 
  TO 
  BOTANY 
  

  

  very 
  different 
  one 
  the 
  next 
  year) 
  often 
  rids 
  the 
  ground 
  of 
  the 
  

   most 
  troublesome 
  weeds. 
  Such 
  weeds 
  as 
  wild 
  oats 
  (fig. 
  246), 
  

   foxtail 
  grass, 
  and 
  wild 
  mustard 
  are 
  very 
  injurious 
  in 
  fields 
  

   of 
  the 
  small 
  grains; 
  they 
  do 
  little 
  damage 
  in 
  cornlields. 
  and 
  

   (hanging 
  the 
  crop 
  from 
  wlieat 
  to 
  corn 
  for 
  a 
  year 
  or 
  two 
  helps 
  

   to 
  reduce 
  these 
  weeds. 
  Many 
  of 
  the 
  worst 
  weeds 
  in 
  grasslands 
  

   and 
  pastures, 
  such 
  as 
  tlie 
  common 
  sorrel 
  (fig. 
  241), 
  wild 
  ear- 
  

   rot, 
  wild 
  parsnip, 
  buttercup, 
  moth 
  mullein, 
  common 
  mullein, 
  

   orange 
  hawkweed, 
  oxeye 
  daisy, 
  and 
  yellow 
  daisy, 
  do 
  little 
  

   harm 
  in 
  cornfields. 
  At 
  times 
  these 
  weeds 
  and 
  many 
  others 
  

   become 
  very 
  harmful 
  in 
  grasslands. 
  If 
  such 
  grasslands 
  are 
  

   plowed, 
  and 
  a 
  cultivated 
  crop, 
  as 
  corn 
  or 
  potatoes, 
  is 
  grown 
  

   for 
  one 
  or 
  two 
  years, 
  these 
  weeds 
  may 
  be 
  effectively 
  removed. 
  

  

  PROBLEMS 
  

  

  1. 
  Name 
  five 
  of 
  tin 
  1 
  worst 
  weeds 
  of 
  cornfields 
  in 
  your 
  region; 
  five 
  

   of 
  fields 
  of 
  small 
  grains; 
  five 
  of 
  grasslands. 
  Which, 
  if 
  any, 
  of 
  these 
  

   weeds 
  are 
  not 
  natives 
  of 
  this 
  country 
  ? 
  

  

  2. 
  What 
  is 
  the 
  most 
  troublesome 
  weed 
  in 
  the 
  gardens 
  that 
  you 
  

   know? 
  Why? 
  What 
  is 
  the 
  best 
  method 
  ut' 
  de>tn>ying 
  it? 
  

  

  3. 
  Give 
  an 
  example 
  of 
  a 
  weed 
  that 
  thrives 
  l>est 
  in 
  \\>-\ 
  soil 
  ; 
  of 
  one 
  

   that 
  will 
  grow 
  in 
  very 
  dry 
  soil 
  ; 
  of 
  one 
  that 
  is 
  little 
  injured 
  by 
  trampling 
  ; 
  

   of 
  one 
  that 
  is 
  so 
  offensive 
  to 
  gra/.ing 
  animals 
  that 
  it 
  is 
  never 
  eaten 
  by 
  

   them; 
  of 
  one 
  that 
  is 
  not 
  killed 
  l>y 
  being 
  uprooted 
  and 
  left 
  exposed. 
  

  

  4. 
  Describe 
  the 
  way 
  in 
  which 
  the 
  seeds 
  or 
  fruits 
  of 
  ten 
  common 
  

   weeds 
  are 
  dispersed. 
  

  

  5. 
  Which 
  of 
  these 
  kinds 
  of 
  seeds 
  are 
  very 
  likely 
  to 
  be 
  bought 
  mixed 
  

   with 
  many 
  weed 
  seeds: 
  corn, 
  ordinary 
  grasses, 
  \\heat, 
  clover, 
  beds? 
  

   Explain. 
  How 
  is 
  the 
  dillicnlty 
  to 
  be 
  avoided? 
  remedied? 
  

  

  6. 
  Give 
  an 
  example 
  of 
  a 
  weed 
  that 
  is 
  troublesome 
  in 
  spite 
  of 
  hav- 
  

   ing 
  no 
  very 
  eliicient 
  means 
  of 
  seed 
  dispersal. 
  

  

  7. 
  Try 
  to 
  give 
  some 
  reasons 
  for 
  the 
  fact 
  that 
  a 
  majority 
  of 
  our 
  

   worst 
  weeds 
  are 
  of 
  foreign 
  origin 
  largely 
  European. 
  

  

  8. 
  Kxplain 
  why 
  rotation 
  of 
  crops, 
  such 
  as 
  plowing 
  a 
  mowing 
  li< 
  M 
  

   and 
  seeding 
  it 
  to 
  corn, 
  tends 
  to 
  destroy 
  weeds. 
  

  

  9. 
  (Jive 
  instances 
  of 
  useful 
  plants 
  of 
  the 
  farm 
  or 
  garden 
  that 
  you 
  

   have 
  found 
  growing 
  like 
  weeds 
  among 
  other 
  crops. 
  

  

  