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JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER. 
January  10,  1901. 
Tf|e  Structure  of  Wood. 
The  internal  structure  of  plants  is  not  strictly  within  the  province 
of  the  gardener,  who  is  interested  almost  exclusively  in  roots,  flowers, 
foliage,  and  fruit.  He  finds  it  necessary  to  become  acquainted  with 
the  minute  structure  of  the  flower,  especially  in  cases  where  he  is 
unacquainted  with  the  name  of  a  plant,  when  he  is  guided  by  the 
arrangement  of  sepals,  petals,  stamens,  and  pistil  to  the  natural  order, 
genus,  and  finally  to  the  species.  Moreover,  before  he  can  study  the 
structure  of  the  woody  stem  of  any  of  the  tenants  of  his  garden  it 
must  either  be  mutilated  or  cut  down.  It  is  not  altogether  a  far 
fetched  idea  that  the  structure  of  wood  may  be  of  use  to  a  gardener, 
because  after  the  fall  of  the  leaf  a  strange  tree  may  be  difficult  to 
identify,  and  a  section  taken  from  a  branch  may  materially  assist  him 
in  referring  it  to  its  species. 
Everyone  must  be  familiar  with  certain  aspects  of  wood,  the  rings 
which  appear  on  a  transverse  section  which  indicate  the  annual 
addition  to  the  bulk  of  a  tree;  the  rays  which,  proceeding  from  the 
pith,  resemble  the  threads  of  a  spidei’s  web,  and  which  appear  as  the 
“  silver  ’’  gram  in  the  plank  ;  and  the  pores  that  make  some  woods 
look  coarse  or,  as  it  is  termed,  “open  grained.”  If  examined  each  of 
these  elements  will  be  seen  to  be  arranged  in  definite  form,  varying 
infinitely  in  size  and  relation  to  each  other  in  different  kinds  of  wood, 
but  practically  constant  in  the  same  species.  If  we  ignore  the 
variation  in  the  breadth  of  the  rings,  which  is  dependent  on  the  vigour 
of  growth  from  time  to  time,  we  shall  find  that  the  rays,  pores,  and 
rings  arrange  themselves  in  different  patterns  or  designs  as  it  were, 
which  may  be  recognised  with  a  little  practice.  To  do  this  it  is 
necessary  to  carefully  smooth  the  surlace  of  the  wood  with  a  sharp 
knife  or  plane,  and  in  cases  where  the  pores  are  extremely  minute  a 
fine  shaving  must  be  cut  sufficiently  thin  to  be  semi-transparent,  an 
easy  matter  if  an  iron  plane  be  u-ed. 
Take,  as  the  most  familiar  example,  a  piece  of  Oak,  and  observe 
that  there  are  two  kinds  of  rays,  some  conspicuous  and  others 
extremely  fine,  and  that  between  them  and  almost  parallel  to  them 
are  branching  lines  of  minute  pores.  In  most  Oaks  there  is  also  a 
prominent  ring  or  band  of  very  large  pores  as  in  our  native  species, 
but  whether  it  lacks  this  latter  feature  or  not,  the  wood  which 
possesses  the  characters  mentioned  is  an  Oak  of  some  sort.  Beech  may 
be  told  by  the  presence  of  rather  prominent  brown  rays  which  do  not 
run  for  long  distances  like  that  of  the  Oak,  but  cross  a  few  of  the 
annual  rings  only  and  taper  to  a  sharp  point  at  each  end,  always 
regarding  them  upon  the  surface  of  a  cross  or  transverse  section. 
Hornbeam  has  an  arrangement  of  the  smaller  pores  recalling  that  of 
the  Oak,  and  also  rays  of  various  sizes,  but  the  larger  ones  are  not 
simple,  but  are  obviously  made  up  of  a  number  of  the  small  white 
rays  crowded  together,  in  addition  to  which  the  outline  of  the  rings  is 
very  boldly  waved.  Some  Oaks  have  wavy  rings  when  young,  but 
they  become  obliterated  and  rounded  off  with  age,  whilst  those  of  the 
Hornbeam  become  more  accentuated  towards  the  outside  of  the 
stem.  One  may  conclude  from  this  that  the  Hornbeam  is  related 
to  the  Oak,  just  as  one  might  do  from  a  comparison  of  the  fruit  or 
flowers. 
The  tissue  of  the  Elm  is  really  most  beautiful.  The  smaller  pores, 
which  run  concentrically  between  the  bands  of  large  pores  indicating 
the  spring  wood,  form  undulating  lines  and  angles,  sometimes  con¬ 
tinuous,  sometimes  broken,  but  always  marking  a  delicate  tracery. 
The  Elms  are  extremely  uniform  in  structure  ai  d  cannot  be  mistaken, 
but  to  differentiate  between  one  Elm  and  another  by  the  character  of 
the  wood  requires  considerable  familiarity  with  each  species  and  the 
use  of  the  microscope. 
The  Maples  are  another  group  in  which  scarcely  any  specific 
differences  can  be  detected,  as  they  all  have  minute  pores  evenly 
scattered  over  the  breadth  of  the  ring  and  enclosed  in  sharply  defined 
compartments,  as  it  were,  by  the  narrow,  but  Very  clear,  straight 
rays,  which  latter  often  produce  an  ornamental  silver  grain  in  the 
plank. 
There  is  another  character  of  importance  to  which  I  have  not  yet 
referred — i.e.,  a  certain  kind  of  soft  tissue  composed  of  larger  and 
looser  elements  than  the  ground  tissue  of  the  wood,  and  which  makes 
its  appearance  as  lines,  patches,  and  zones  in  great  variety.  All  the 
woody  plants  of  the  Pea-flower  family  exhibit  this,  as  may  be  seen  in 
the  stems  of  the  Gorse,  the  Broom,  or  the  Laburnum,  where  a  kind  of 
cruciform  pattern  will  be  observed  amongst  which  the  pores  are  set. 
The  Acacia  or  Robinia  shows  this  very  beautifully  in  its  brown,  or 
greenish-brown,  heartwood,  and  it  is  worth  sacrificing  just  a  small 
branch  to  observe  it.  A  fifth  character  of  lesser  moment  is  the 
presence  or  absence  of  Small  brown  patches  or  flakes.  These  are  the 
result  of  an  effort  of  the  tree  to  heal  the  wounds  caused  by  grubs 
which  live  beneath  the  bark,  failing  which  those  trees  whose  wood 
is  toothsome  to  the  beetle  tribe  would  never  produce  anything  but 
timber  riddled  with  holes.  They  may  be  seen  in  such  woods  as  Birch, 
Alder,  Blackthorn  and  Hawthorn,  and  sometimes  gives  rise  to  a 
multitude  of  false  rays  which  proceed  in  a  brush-like  fashion  from  the 
outer  side  of  the  flake. 
It  must  not  be  assumed  that  because  certain  woody  plants  have  a 
family  likeness  in  their  timber  that  there  exists  a  means  of  classification 
by  their  structure.  The  science  is  by  no  means  so  far  advanced,  and 
the  presence  of  conspicuous  differences  in  the  same  tribe  make 
anything  except  an  artificial  classification  impossible  at  present,  but 
perhaps  a  little  order  may  be  arrived  at  by-and-bye.  We  may, 
however,  draw  a  few  broad  distinctions,  as  between  the  Conifers  and 
the  broad-leaved  trees,  which  hold  good  throughout.  The  wood  of  the 
Conifers  never  possesses  true  pores  or  vespels,  though  many  have  pores 
of  a  different  kind,  called  Rezin  pores.  These  latter  are  usually  more 
sparing  in  their  numbers  than  true  pores,  and  are  always  more 
numerous  in  the  summer  and  autumn  zones  than  in  the  spring  wood 
or  inner  edge  of  each  annual  ring.  In  the  broad-leaved  trees,  on  the 
contrary,  although  the  pores  may  be  evenly  scattered  throughout  the 
breadth  of  each  ring  in  certain  cases,  they  are  never  more  numerous  in 
the  outer  portion  of  the  ring  than  in  the  inner.  The  structure  of  the 
wood  of  the  Conifers  is  very  simple,  and  hence  provides  few 
distinctions  which  can  be  employed  to  distinguish  one  kind  from 
another.  Amongst  the  Pines,  for  example,  it  is  almost  hopeless.  The 
rays  are  almost  always  extremely  fine,  the  ground  tissue  is  very 
uniform,  and  the  pore  tracery  and  patches  of  soft  tissue,  which  aid  us 
so  much  in  many  other  natural  orders,  is  always  absent.  The  wood  ot 
Palms  being  endogenous,  is  readily  distinguished  from  either  exogens 
or  Conifers.  There  is  a  complete  absence  of  the  radial  or  concentric 
appearance  of  the  wood,  of  the  two  latter  an  irregular  mass  of  isolated 
bundles  is  present  instead,  as  will  be  seen  on  cutting  any  cane  or 
bamboo. 
If  a  piece  of  the  wood  of  a  Conifer  or  broad-leaved  tree  be  cut 
in  a  Vertical  direction,  or  plankwise  as  it  is  called,  we  get  two  different 
forms  of  structure,  one  if  the  cut  be  across  the  centre  of  the  tree  in  the 
plane  of  the  rays,  and  another  if  cut  away  from  the  centre  at  right 
angles  to  the  rays  and  tangentially  with  the  rings.  In  the  first  case 
the  familiar  silver  grain,  which  is  caused  by  fragments  of  the  rays 
remaining  on  the  surface,  is  seen,  and  in  the  second  the  ends  of  the 
rays  only  are  visible,  hence  variation  in  the  direction  of  the  cut  may 
produce  any  combination  between  these  two  forms,  so  that  usually  no 
two  planks  cut  from  a  tree  exactly  resemble  each  other.  Hence  it 
requires  long  experience  to  tell  the  names  of  even  our  common  timbers 
by  their  appearance  in  the  plank.  The  pore-rings  in  the  spring  wood 
show  up  as  bands  of  more  or  less  coarse  scratches  and  the  rays  as 
lines  of  varying  depth.  In  the  Beech  we  see  them  as  shallow  brown 
flakes  which  diminish  to  tiny  lines  as  the  section  becomes  more  at 
right  angles  to  them,  while  in  the  Oak  they  may  be  anything  from 
deep  lines  inches  long  to  broad  deep  plates  of  shining  silver  grain.  All 
of  these  points  have  their  value  as  specific  characters,  though  there 
is  no  section  that  gives  us  as  much  information  as  the  cross  section, 
which  in  many  cases  suffices  alone. — Herbert  Stone,  F.L.S. 
On  Soil  and  Mannre. 
The  spring  is  at  hand,  and  a  corresponding  amount  of  interest 
will  soon  be  felt  by  all  parties  concerned  in  the  culture  of  the  soil. 
Gardening  has  made  very  rapid  strides  of  recent  years,  its  professors 
being  great  readers,  and  horticultural  literature  has  been  doing 
its  best  to  keep  pace  with  the  spirit  of  the  times  in  satisfying  these 
readers’  demands.  To  these  growers  I  would  point  out  some  important 
aspects  in  relation  to  soil.  There  has  latterly  been  much  attention 
paid  to  the  question  of  the  food  of  plants.  This  has  led  to  scientific 
investigation  as  to  the  relative  merits  of  manures,  aod  we  have  seen 
results  which  our  ancestors  would  have  deemed  miraculous. 
Still  a  vital  point  connected  with  the  permanent  amelioration  of 
the  soil  lies  in  the  background — viz.,  the  improvement  of  the 
mechanical  texture  of  soils  or  the  improvement  of  their  staple.  This 
is  the  grand  basis  of  all  improvement,  to  which  even  the  employ¬ 
ment  of  manure  is  a  subordinate  matter.  As  in  the  making  of  good 
pastry,  so  in  the  treatment  of  soil,  the  working  of  the  material 
counts  for  as  much  and,  sometimes,  even  more  than  the  prodigal 
addition  of  rich  ingredients.  The  raising  of  the  unexhausted  elements 
of  the  subsoil,  and  the  free  admission  of  heat  and  air  to  assist  decom¬ 
position,  play  a  large  part  in  the  process,  and,  though  they  entail 
labour,  must  not  be  shirked  on  that  account. 
Everybody  knows  that  open  sandy  soils  are  hungry  soils; 
everybody  also  knows  that  it  is  little  use  multiplying  the  amount  of 
manures  in  stagnant  clays  or  boggy  soils  unless  drained.  Here,  then, 
we  come  to  the  matter  of  mechanical  texture,  which  is  of  vast 
importance.  Thorough  drainage  must  precede  all  attempts  at  improving 
the  texture  in  the  case  of  adhesive  soils,  whilst  the  sandy  ones  will 
