270 
JOURNAL  OF  HORTTCULTURE  AND  COTTAGE  GARDENER, 
]March  26,  19C3. 
Elementary  Notes  on  Plant  Distribution. 
{Continued  from  puge  231.) 
The  amount  of  moisture  also  has  its  due  effect  in 
limiting  the  range  of  a  plant ;  for  if  it  be  one  that  requires  a 
humid  atmospliere,  it  cannot  pass  the  barrier  presented  by  a 
very  dry  climate,  even  though  the  temperature  and  composition 
of  the  soil  is  suitable  for  it.  On  the  other  hand,  if  it  be  a  plant 
that  delights  in  a  dry  climate,  one  that  has  a  humid  atmosphere 
.  and  abundant  rainfall  would  prove  fatal  to  it.  Thus  it  is  that 
in  regions  which  are  humid  or  dry  respectively  we  find  in  each 
a  totally  different  type  of  vegetation,  climate  having  impressed 
a  different  facies  upon  it  in  each  case.  This  is  especially  notice¬ 
able  in  the  tropical  and  sub-tropical  parts  of  the  earth,  because 
the  greater  heat  of  those  regions  accentuates  the  distinction.  In 
the  portions  where  there  is  a  great  rainfall  and  a  very  humid 
atmo.'.^phere,  such  as  in  the  Malay  Archipelago  and  basin  of  the 
Amazon  and  its  tributaries,  there  we  invariably  find  forest  pre¬ 
dominating,  the  trees  of  great  Ijeight,  with  large  leaves,  and  the 
undergrowth  also  with  well-developed  foliage;  whilst  in  the 
drier  portions,  such  as  the  interior  of  Mexico  and  South  Africa, 
where  the  rainfall  is  small,  an  entirely  different  type  of  vegetation 
is  met  with.  The  trees  are  usuallj’  of  comparatively  low  stature, 
their  leaves  and  those  of  the  abundant  dwarf,  shrubby  plants, 
are  generally  of  small  size,  and  succulent  and  leafless  plants  fre¬ 
quently  form  a  conspicuous  clement  in  the  vegetation.  In  the 
humid  climate  plants  require  to  get  rid  of  much  of  the  water  in 
their  tissues,  after  using  up  the  mineral  matter  contained  in  it 
for  building  up  their  own  rapidly  increasing  structure.  Here 
the  use  of  their  large  loaves  is  seen,  for  by  presenting  a  larger 
evaporating  surface,  they  accomplish  this  the  more  readily. 
Whilst  in  a  dry  climate  irlants  require  to  prevent  too  much  water 
evaporating  from  their  tissues,  hence  the  reduction  of  leaf  sui’- 
face  or  tendency  to  become  leafless  or  succulent  with  a  thickening 
and  hardening  of  the  epidermis.  The  difference  in  the  plants 
of  a  humid  and  dry  climate  respectively  are  usually  so  well 
marked  that  with  a  very  little  experience  it  is  easy  to  tell  from 
the  appearance  of  the  plant  which  kind  of  climate  it  came  from. 
.Kven  in  Britain  we  find  in  a  small  degree  these'  two  types  of 
vegetation;  although  here  they  are  due  to  the  character  of  the 
situation  and  soil,  not  to  a  difference  of  climate,  for  the  Heather. 
Furze,  Thyme,  Euphrasia,  Ac.,  of  our  dry  sandy  commons  and 
exposed  hillsides,  from  which  the  rain  soon  runs  off,  are  distinct 
in  type  from  the  larger-leaved  plants  of  our  woods  and  more 
humid  localities. 
Thus,  climate  acts  upon  vegetation,  and  produces  the  kaleido¬ 
scopic  changes  of  scene  we  may  pass  through  in  going  from  the 
tropics  to  the  poles.  For  as  plants  are  adapted  for  different 
amounts  of  heat,  moisture,  and  light,  so  we  find  them  grouped  in 
belts  around  the  earth.  Such  as  Palms,  Tree  Ferns,  treei-like 
Monocotyledons  (Dracaena,  Cordyline,  Aloe,  Pandanus,  Ac.),  large 
woody  climbing  plants.  Figs,  Begonias,  Laurels,  Cacti,  succulent 
Euphorbias,  epiphytic  Orchids,  Bromeliads,  Aroids,  Crinum,  Ac., 
being  characteri.stic  of  the  liottcr  regions  of  the  earth.  Travelling 
polewards  we  pass  over  plains  covered  with  grass  and  herbaceous 
perennials,  through  forests  of  which  various  species  of  Oak,  Fir, 
Cedar,  Juniper,  Ash,  Elm,  Walnut.  Beech,  Mai^le,  Plum,  Cherry, 
Ac.,  are  characteristic;  through  pastures  gay  with  Buttercups, 
Harebell,  and  Daisy,  or  over  moorland  or  common  covered  with 
purple  Heather  or  golden  Furze,  to  regions,  with  an  arctic 
climate,  where  trees  are  absent  and  only  a  very  dwarf  vegetation 
is  present. 
As  we  pa.ss  from  tropic  to  pole,  and  comparing  equal  areas,  we 
shall  note  a  gradual  decrease  in  the  number  of  species.  For  ex¬ 
ample,  if  we  compare  France  and  Norwaj'  and  Sweden,  two  areas 
in  different  latitudes,  near  enough  alike  in  size  for  our  purpose, 
and  of  which  the  floras  are  well  known,  we  find  that  France,  with 
an  area  of  201,000  square  miles,  has  about  4,850  species  of  flower¬ 
ing  plants  and  Ferns;  whilst  Sweden  and  Norway  together,  with 
the  larger  area  of  over  290,000  square  miles,  has  only  about  1,920 
species,  or  loss  than  half  the  number.  Corresponding  with  a 
reduction  of  .species  there  is  also  a  reduction  in  stature;  for  in- 
jstance,  the  Scotch  Fir  and  the  Birch  in  Southern  Europe,  in 
favoured  localities,  will  attain  a  height  of  100ft  and  60ft  respec¬ 
tively,  whilst  at  their  northern  limits  they  become  dwarfed  to 
rpiite  small  trees  or  shrubs. 
Now,  in  passing  through  these  changes  of  scene  we  shall  have 
traversed  some  TOdeg  of  latitude,  but  by  ascending  a  very  high 
mountain  we  inay  pa'-s  through  a  similar  change  of  scene  in  a 
.iourney  of  a  few  miles.  Some  of  the  peaks  of  the  Himalayas 
furnish  an  excellent  example  of  this.  At  their  foot  and  on  their 
lower  spurs  we  pass  through  a  tropical  forest  or  jungle  in  which 
Balms,  Tree  Ferns,  Figs,  Bamboos,  Orchids,  and  other  tropical 
types  are  present;  higher  up  more  temperate  types,  such  as 
Bhododendron,  Berberry,  Aconite,  Alagnolia,  Hvpericum,  Oaks, 
hlap!  cs.  Pyrus,  Yew,  Pines,  and  Silv’er  Firs.  Ac.,  are  met  with; 
whilst  on  the  higher  iiarts  below  the  perpetual  snow  trees  are 
absent,  and  dwarf  species  of  characteristic  arctic  genera  are 
found,  such  as  Saxifraga,  Draba,  Arenaria.  Potentilla,  Gentiana, 
and  many  others,  together  with  Mo.sses  and  Lichens.  On  every 
mountain  of  stifficient  altitude  in  any  part  of  the  world  a  similar  1 
change  from  a  tropical  or  temperate,  according  to  latitude,  to  an 
arctic  vegetation,  is  seen  as  we  a.scend ;  the  colder  climate  of  the 
higher  elevations  acting  on  plant  life  in  the  same  way  as  on  pass¬ 
ing  from  tropic  to  pole. 
And  there  is  also  a  certain  correspondence  between  the 
latitudinal  range  of  a  plant  and  the  altitude  at  which  it  is  found 
ujjon  a  mountain.  For  instance,  the  Chamomile  (Anthemis 
nobilis)  does  not  ascend  to  1,000ft  above  sea  level  in  the  south 
of  England,  and  does  not  extend  beyond  the  south  of  Scotland — 
this  is  a  heat  lover,  whilst  in  Saxifraga  oppositifolia  we  have 
an  example  of  a  plant  that  prefers  a  cold  climate;  thus,  in  the 
Arctic  and  northern  regions  it  is  found  at  sea  level,  southward  it  is 
only  found  at  increasingly  higher  elevations,  with  a  teni- 
perature  and  atmospheric  conditions  approaching  those  of  its 
northern  home,  until  in  the  Alps,  except  where  brought  down  by 
streams,  it  only  occurs  at  several  thousand  feet  above  sea  level. 
Similarly  there  also  occurs  the  dwarfing  of  the  plant  as  it 
ascends  to  higher  and  colder  regions.  Fitzroya  patagonica  is  a 
striking  example  of  this.  It  is  a  native  of  the  Andes  of  Southern 
Chili,  and  at  the  lower  elevations  attains  a  height  of  about  lOOft, 
but  at  higher  elevations  it  gradually  becomes  less  and  less  in 
•stature,  until  at  its  uppermost  limit,  near  the  perpetual  snow 
line,  it  is  stated  to  be  dwarfed  to  a  height  of  only  4in  to  Gin.  So 
that  at  its  lower  limit  of  growth  the  traveller  has  the  tree  tower¬ 
ing  far  above  his  head,  whilst  at  its  upper  limit  he  can  actually 
w^lk  over  it.  This,  of  course,  would  only  obtain  with  such  plants 
as  have  a  sufficiently  elastic  constitution  to  withstand  a  consider¬ 
able  range  of  temperature.  Many  plants  are  not  .so  flexible, 
being  strictly  limited  to  comparatively  narrow  belts  on  the 
mountain  sides,  as  for  example  the  Cinchonas,  some  of  which  grow 
in  belts  on  the  slopes  of  the  Andes  of  not  more  than  a  few 
hundred  feet  of  altitudinal  breadth. — N.  E.  Brown.  F.L.S. 
(To  be  continued.) 
- - • - 
Horticulture  in  Devonshire. 
The  work  of  1903  will  be  very  late^  here,  if  one  may  judge  by 
the  present  condition  of  the  land.  Owing  to  the  late-digging 
habit  of  the  people  in  Devonshire,  I  fear  that  much  of  the  plant¬ 
ing  will  not  be  completed  by  the  end  of  Api'il.  If  deeper  spade 
work  were  entered  upon,  say,  at  the  beginning  of  the  year,  we 
coidd  easily  get  our  seeds  in  quite  three  weeks  sooner.  The  bad 
crops  of  Bed  C'lover,  and  some  other  seeds,  grown  in  Devon  in 
1902,  teach  the  le.sson  of  more  culture.  Deeply  .stirred  soils 
allow  moisture  to  pass  through  the  .surface  into  the  sub.soil. 
leaving  the  .surface  much  warmer  and  drier.  Messrs.  Veitch  and 
Son.  of  Exeter,  show  the  need  of  this  work  in  their  annual  report 
on  the  seed  crops  and  harvest  of  the  past  year,  when  they  say, 
“Practically  none  of  last  year’s  crop  was  .saved  in  Devon  or 
Somerset,  and  we  have  had  to  rely  on  the  eastern  counties  for 
samples  of  high  or  a.verage  quality.  Cowgrass  is  equally  scarce. 
Mhite  Dutch  C'lover  is  the  shortest  crop  for  very  many  years.” 
Our  rainfall  is  double  that  of  the  eastern  counties.  I  have, 
to-day.  planted  Potatoes  for  an  early  crop,  in  a  parish  not  far 
from  Barnstaple.  The  people  said  that  they  had  never  seen  such 
work  done.  The  manure  was  spread  on  the  surface,  and  super¬ 
phosphate  also;  then  the  land  was  dug  a  good  spade’s  depth. 
The  garden  line  was  kept  on  the  newly  dug  soil,  instead  of  being 
at  tlie  back  of  the  man  digging.  When  sufficient  land  had  been 
dug  to  cut  a  level  for  the  seed  Potatoes  to  lie  on,  the  line  was 
brought  fonvard  for  the  purpose  of  making  a  straight  cut  across 
the  dug  soil.  After  planting  the  Potatoes,  I  proceeded  to  dig 
acro.ss  the  garden,  turning  the  soil  on  to  the  Potatoes,  so  hand¬ 
ling  the  spade  as  to  put  tlic  good  black  soil  just  on  to  the  seeds, 
and  the  bottom  part  of  the  soil  on  the  surface,  tlius  exposing  it 
to  the  air.  At  each  .spadeful  I  brought  up  soil  that  had  never 
been  exposed.  This  subsoil,  of  course,  will  improve,  and  what¬ 
ever  the  summer  may  be,  the  deeper  soil  will  hold  more  water, 
and  excess  of  rain  will  go  down  lower,  leaving  the  surface  soil 
drier,  in  measure  more  like  the  soil  of  drier  counties.  Thus 
throwing  off  the  moisture  our  scedsuvill  ripen  better  and  become 
of  greater  value. 
Mangold,  Swede,  and  Turnip  have  yielded  well.  Those  who 
have  seen  Messrs.  Peter  Veitch  and  Sons’  Mangolds  need  not  be 
told  how  good  they  are.  Their  seed  manager  tells  me  that  local 
growers  should  sow  thicker  than  usual.  Mr.  Veitch’s  idea  is  that 
those  gardeners  who  were  tempted  by  a  few  fine  days  to  .sow 
seeds  will  regret  having  done  .''O.  becau.se  the  heavy  rains  will 
sodden  the  ground  and  destroy  much  of  the  seed  of  some  crops 
sown . 
Mr.  F.  W.  E.  Shrivell,  F.L.S. .  of  Golden  Green.  Tonbridge,  i-; 
doAvn  for  a  lecture  on  manures  at  tlie  forthcoming  meeting  of  the 
Devon  and  Exeter  Gardeners’  Association  this  Aveek.  If  Mr. 
Shrivell  be  as  instructive  as  he  AA'as  on  his  last  visit,  the  members 
AA’ill  learn  much.  They  AA'ould  do  Avell  to  take  notebooks.  One 
feels  the  force  of  figures  AA'hen  they  confirm  one  in  mixing  one’s 
OAAii  manures.  I  look  for  a  good  meeting  on  the  occasion  of  this 
return  visit  of  Mr.  Shrivell. — X. 
