﻿338 
  

  

  INTRODUCTION 
  TO 
  BOTANY 
  

  

  farther 
  westward. 
  A 
  few 
  weeds, 
  like 
  the 
  buffalo 
  bur 
  (fig. 
  244), 
  

   have 
  made 
  their 
  way 
  eastward 
  from 
  the 
  Great 
  Plains. 
  

  

  315. 
  How 
  to 
  avoid 
  and 
  

   destroy 
  weeds. 
  Jt 
  is 
  often 
  

   easier 
  to 
  keep 
  weeds 
  out 
  

   of 
  cultivated 
  ground 
  than 
  

   to 
  destroy 
  them 
  after 
  they 
  

   get 
  a 
  foothold 
  there. 
  The 
  

   principal 
  means 
  of 
  avoid- 
  

   ing 
  weeds 
  are 
  to 
  plant 
  as 
  

   few 
  weed 
  seeds 
  as 
  possi- 
  

   ble 
  and 
  to 
  allow 
  few 
  to 
  be 
  

   planted 
  by 
  natural 
  agen- 
  

   cies. 
  This 
  means 
  that 
  the 
  

   seeds 
  used 
  for 
  the 
  farm 
  

   and 
  garden 
  shall 
  be 
  as 
  

   free 
  as 
  possible 
  from 
  

   weed 
  seeds, 
  that 
  all 
  ma- 
  

   nure 
  used 
  shall 
  contain 
  

   as 
  few 
  weed 
  seeds 
  as 
  pos- 
  

   sible, 
  and 
  that 
  all 
  spots 
  

   which 
  might 
  serve 
  as 
  

   breeding 
  places 
  for 
  weeds 
  

   must 
  be 
  carefully 
  watched 
  

   and 
  prevented 
  from 
  seed- 
  

   ing 
  the 
  adjacent 
  ground. 
  

   Neglected 
  fence 
  rows 
  and 
  

   other 
  bits 
  of 
  uncultivated 
  

   land 
  may 
  grow 
  enough 
  

  

  FIG. 
  246. 
  Couch 
  grass, 
  one 
  of 
  the 
  worst 
  weeds 
  of 
  the 
  northeastern 
  states 
  

  

  It 
  is 
  rapidly 
  propagated 
  by 
  its 
  long 
  rootstocks 
  (rh). 
  Note 
  the 
  manner 
  in 
  which 
  

   young 
  shoots 
  (a, 
  6, 
  c) 
  are 
  shown 
  arising 
  from 
  the 
  nodes 
  of 
  the 
  rootstock 
  

  

  