February  25,  1904. 
16L 
JOUBNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER. 
effect  was  not  apparent  till  the  second  year.  Another 
lovely  blue-flowered  plant  (an  annual)  is  Ipoinoea  rubro- 
cserulea  var.  Heavenly  Blue,  whose  bell-shaped  flowers  are 
exceedingly  bright  and  beautiful.  The  seeds  in  this  case 
were  sown  in  Alarch  and  grown  on  for  flowering  in 
September.  The  slender,  twining  shoots  are  taken  around 
a  balloon-frame.  A  large  share  of  the  gardener’s  efforts 
is  devoted  to  preparing  a  September  display  for  the 
home-coming  of  the  family,  and  subjects  have  to  be  chosen 
to  fit  in,  so  to  speak,  with  that  particular  season.  Still, 
another  subject,  the  seeds  of  which  had  been  sown  in 
March,  was  Torrenia  Fournieri,  the  growths  of  Avhich  were 
spreading  rampantly  in  open-air  frames  in  September.  One 
of  the  finest  features  in  the  garden  was  a  Thyme  walk, 
edged  on  either  side  with  Campanula  persicifolia  alba. 
The  main  points  of  general  interest  having  been  re¬ 
viewed  (though  inadequately)  it  may  add  to  the  quality  of 
usefulness  of  these  notes  to  append  a  list  of  the  main 
subjects  relied  on  for  a  September, display.  These  include 
perennial  Asters — horizontalis,  acris,  cordifolius,  and  others 
Relationship  of  Woods  to  Domestic  Water  Supplies. 
Tills  subject  has,  for  more  than  twenty  years,  occupied  nnuh 
of  the  attention  of  Forest  Experimental  Stations,  especially  in 
Germany,  France,  Austria,  and  Switzerland;  and  in  view  of  its 
^  importance  the  conclusions  arrived  at  may  be  usefully  summarised. 
I  It  has  been  asserted,  and  theoretically  the  contention  is  doubt- 
’  less  correct,  tliat  masses  of  woodland  increase  the  rainfall.  'fhe 
j  causes  of  this  result  are  sought  for  in  the  reduction  of  tempera- 
1  ture  associated  with  forests,  and  in  the  greater  absolute  and 
relative  humidity  of  the  air  in  wood.s.  But  although  it  may  he 
possible  to  obtain  experimental  proof  by  means  of  elaborate  and 
long-continued  observations  in  a  region  where  extensive 
afforestation  or  deforestation  is  taking  place,  it  may  at  once  be 
said  that  such  tree-planting  as  is  practically  possible  in  Britain 
can  have  no  appreciable  influence  on  the  rainfall.  Tree.s  do,  liow- 
ever.  under  certain  conditions  of  the  atmosphere,  condense  dew 
on  their  leaves  and  branches,  and  this  effect  may  often  be  seen 
in  the  wet  state  of  the  ground  underneath  trees  on  a  foggy 
morning,  when  the  surface  elsewhere  is  comparatively  dry. 
But  the  case  is  materially  different  where  the  fate  of  the  rain 
and  SHOW  that  fall  on  a  tract  of  wood- 
laiid  is  considered.  The  foliage, 
branches,  and  stems  of  the  trees  inter¬ 
cept  much  of  the  rain  and  snow  so  that 
it  never  reaches  the  ground  at  all,  the 
amount  so  intercepted  usually  ranging 
from  30  to  45  per  cent,  of  the  total, 
but  much  depends  on  the  character  of 
the  rainfall,  and  on  the  species  of  the 
tree.  In  a  district  of  heavy  annual 
rainfall  a  smaller  in'oportiou  of  the 
precipitations  is  caught  by  and 
evaporated  from  the  trees  than  where 
the  rainfall  is  light.  Similarly  in  the 
case  of  heavy  and  long-continued  rain, 
as  contrasted  with  gentle  showers;  in 
the  latter  case,  in  fact,  but  little  of 
the  water  reaches  the  ground  througb', 
'the  leafy  canopy  of  a  dense  forest. 
Then  again  much  depends  on  the  kind 
of  tree,  evergreens  intercepting  more 
water  throughout  a  year  than  de¬ 
ciduous  trees,  and  a  larger  proportion 
of  the  rainfall  is  evaporated  from  the 
leaves  and  branches  in  summer  than  in 
wiiiter. 
Bub  although  lesi  rain-water 
reaches  the  soil  of  a  wood  than  finds 
its  way  to  the  ground  in  the  open 
country,  the  moisture  in  the  soil  is 
much  better  con, served  in  the  former 
th^n  in  the  latter  case.  Long-con¬ 
tinued  ob.servations  have  shown  that 
more  water  drains  from  a  wooded  area 
than  from  one  devoid  of  trees.  The 
greater  abundance  of  water  in  forest 
soil,  in  spite  of  the  trees  intercepting 
a  large  proportion  of  the  rainfall,  is 
due  partly  to  the  reduction  of  evapora¬ 
tion  owing  to  the  exclusion  of  the 
sun’s  rays  by  the  foliage,  partly  to  tl)e 
air  in  a  forest  being  more  humid,  and 
thus  better  fitted  to  discourage  evaporation,  and  partly  to  the 
absorbent  and  retentiye  character  of  the  decaying  vegetable 
matter  that  covers  the  ground  of  a  dense  and  well-managed 
wood.  The  lace-work  of  tree  roots,  too,  that  occupy  the  soil  of 
a  forest,  offers  mechanical  resistance  to  the  rapid  surface-flow  of 
water.  It  is  also  to  be  noted  that  roots  penetrate  to  great 
depths,  and  when  they  die  they  leave  holes  through  which  water 
readily  penetrates  from  the  surface.  The  friable  condition  of 
the  soil  of  a  wood,  too,  permits  ready  percolation  of  water, 
whereas  in  the  open  country  the  denser  character  of  the  surface 
of  the  ground  is  less  favourable  to  the  entrance  of  water.  The 
consequence  is  that  .streams  in  a  wooded  country  are  not  so  subject 
to  rapid  rises  and  falls,  the,  flo\v  being  maintained  moi’e  equably 
throughout  the  year.  Where  water  supply  for  domestic  or 
industrial  purposes  is  concerned,  the  avoidance  of  violent  freshets 
on  the  one  hand,  and  .scanty  flow  on  the  other,  is  alike  desirable. 
Not  only  may  the  water  of  sudden  and  heavy  floods  be  lost  owing 
to  the  incapacity  of  the  reservoir  to  contain  it,  but  such  floods 
have  also  the  disadvantage  of  carrying  much  mud  and  similar 
material  in  suspension,  and  this  gradually  silts  up  reservoir.s, 
besides  entailing  increa.sed  expenditure  in  filtering. 
It  may  be  pointed  out  that  the  water  of  a  reservoir  surrounded 
by  well  stocked  woodland  is  not  subjected  to  the  same  amount 
of  violent  agitation  during  gale.s  as  is  the  case  when  such  shelter¬ 
ing  agency  is  absent.  The  mud  and  silt  deposited  on  the  bottom, 
and  especially  along  the  margin,  is  consequently  left  compara- 
Allosorus  crispus,  the  Parsley  Fern.  (See  page  158.) 
— Callistephus  hortensis  (parent  type  of  the  China  Asters, 
and  fine  for  naturalising  in  woody  glades).  Verbena  venosa. 
Phloxes,  Gladioli,  Delphinium  nudicaule  (scarlet),  and 
I).  Queen  of  the  Blues  (both  spring  sown).  Lobelia  cardi- 
nalis.  Dahlias,  Koses,  Clematises,  Helenium  Miss  Mellish, 
and  others ;  Hollyhocks,  Lilium  tigrinum,  Pentstemons 
(spring  sown,  treated  as  annuals),  Physalis  Alkekengi, 
Tagetes  signata  pumila.  Lavatera  trimestris  rosea.  Sweet 
Peas,  Brachycome  iberidifolia,  Erigeron  mucronatus, 
Bhodanthes,  Helichrysums.  Ammobium  alaturn  grandiflorum, 
Gaillardia  grandiflora,  Colchicum  speciosum,  Amaryllis 
Belladonna,  Heliotropes,  Pentstemon  barbatus,  and  Nico- 
tiana  affinis. 
In  tazzas  or  so-called  vases,  on  parapets,  there  are  Ivy¬ 
leaved  and  Zonal  Pelargoniums,  early  flowering  Chrys¬ 
anthemums,  Lobelia  erinus  (varieties),  scented  Pelargo¬ 
niums,  Fuchsias,  Abutilons.  Salvia  splendens,  Lilies,  and 
Marguerite  Carnations.  Indoors  about*  this  season  the 
early-flowering  Chrysanthemums  and  Lilium  speciosum  are 
chiefly  relied  on.  In  winter  there  are  late  Chrys¬ 
anthemums,  Begonia  Gloire  de  Lorraine,  B.  Agathea  (for 
tiny  jars),  Poinsettias,  Dscdalacanthus  and  Jacobinias  ; 
while  forced  bulbs  furnish  most  of  the  early  spring  display. 
— J.  H.  I). 
