^""Fch^mT"'  \  Migration  of  Plants  from  Europe  to  America,    i  t  3 
vation.  It  is  only,  therefore,  among  the  smaller  and  more  insignificant  plants  that 
the  facts  here  detailed  can  be  looked  for,  and  accordingly  of  such  our  list  altogether 
consists.  It  may  be  that  the'  forest  trees  of  Europe,  or  some  of  them,  will  one  day 
grow  wild  here.  But  the  life  of  a  tree  is  so  long,  and  its  growth  so  slow,  that  the 
experiment  cannot  be  said  to  have  been  yet  made.  So  far  from  planting  and  prop- 
agating European  trees,  men  are  bent  in  most  parts  of  the  country  upon  destroying 
their  own.  The  present  generation  has  not  outgrown  that  insane  hatred  ot  trees 
which  possessed  the  past,  and  was  perhaps  an  almost  unavoidable  result  ot  the  seve- 
rity of  their  struggle  with  the  primeval  forest.  Timber  is  still  contemptuously 
termed  "lumber."  No  respect  is  felt  for  it,  and  consequently  no  European  tree,  if 
trying  to  run  wild,  would  stand  much  chance  of  life  during  the  attempt.  A  high 
authority  on  forest  trees  in  this  country  has  informed  the  writer  that  in  his  experi- 
ence some  European  species  have  grown  better  than  the  American  species  ot  the 
same  genus— that  the  English  beech  and  larch,  for  example,  surpassed  the  native 
beech  and  the  tamarack.    Time  alone  can  prove  this  point. 
The  comparison,  therefore,  must  be  made,  and  can  only  be  made  justly,  between 
the  weeds  of  the  two  continents,  or  plants  which  come  very  near  them  and  may  be 
called  almost  weeds.  By  the  term  "weed"  we  mean  those  plants  to  which  the  sur- 
roundings are  so  suitable  that  they  increase  and  multiply,  year  after  year,  more 
rapidly  than  others  by  which  they  are  surrounded.  Entering  into  details,  the  soil 
affords  them  the  nourishment  they  need  5  the  spring  frosts  do  not  kill  them,  or  they 
bud  and  grow  only  when  this  danger  is  passed  5  they  ripen  their  seed  in  quantity 
sufficient  before  the  winter  sets  in  5  the  heat  of  summer  does  not  scorch  them,  nor 
the  cold  of  winter  destroy  their  roots  or  seeds  5  they  are  not  so  much  injured  by 
insects  as  to  preclude  their  coming  to  maturity  5  while  their  flowers  are  sufficiently 
visited  by  insects  to  insure  the  fertilization  ot  their  seeds,  or  else  they  spread  so 
rapidly  by  underground  stems  as  to  render  seed  unnecessary.  Granted  all  these 
conditions,  and  we  have  weeds  of  the  first  order,  while  the  failure  of  any  one  or 
more  of  tliem  may  reduce  such  a  weed  to  the  position  of  a  very  har  mless  and  com- 
paratively rare  plant.  In  fact,  the  great  abundance  of  a  weed  or  wild  flower  in  one 
year,  and  its  scarcity  in  another,  is  often  due  to  its  lacking  one  or  more  of  these 
requisites.  Weeds  are  the  homely  plants  of  a  country,  using  the  word  in  its  true  and 
original  sen^e.  A  plant  that  is  perfectly  comfortable  in  its  surroundings,  if  possess- 
ing considerable  power  of  reproduction,  becom;;s  master  of  the  situation,  and  is  a 
uueed. 
The  weeds  of  different  countries  must  therefore  differ  because  their  conditions 
differ.  For  the  same  reason  the  weeds  of  different  ages  must  also  differ.  Climate 
changes  as  geological  time  passes  by,  and  all  plants  are  not  able  to  adapt  themselves 
to  these  changes.  It  is  frequently  the  case  that  a  man  placed  in  new  circumstances 
is  quite  unable  to  adjust  himself  to  them.  His  nature  is  not  sufficiently  plastic.  So 
with  plants.  A  wide  range  in  time  or  space,  with  changing  conditions,  can  only  be 
enjoyed  by  a  plant  whose  nature  is.  plastic  or  capable  of  change.  Place  a  weed  of 
stiff  or  unyielding  nature  in  less  favorable  conditions  and  it  cannot  adapt  itself  to 
them.  It  becomes  unhealthy  and  lingers  on,  as  it  were,  by  sufferance  among  stronger 
neighbors — no  longer  a  weed — or  it  speedily  dies  out.    But  a  weed  possessing  a 
