408  Medicinal  Plants  at  Banbury.  {Km2°Z'^i™' 
of  about  four  years  old  yield  from  one  and  a  half  to  two  tons  of  dried 
root  per  acre,  but  ten  year  old  plants  will  yield  about  five  tons  per  acre. 
The  drying  is  by  no  means  an  easy  task.  The  roots  are  dug  up  in 
hot  weather,  at  any  time  between  July  and  October,  and  for  the  first 
fortnight  are  exposed  to  a  current  of  air  on  wicker  baskets  in  a  covered 
shed.  They  are  then  removed  to  the  drying-room,  where  they  are 
dried  gradually  but  thoroughly  for  about  six  weeks,  by  means  of  a  cur- 
rent of  heated  air.  This  part  of  the  process  requires  great  care;  lest 
the  outer  portion  should  be  dried  too  rapidly,  while  the  interior  is  still 
moist.  The  large  central  portion,  or  tap  root,  furnishes  the  pieces 
known  in  trade  as  "fine  large  flats"  and  "fine  large  rounds."  The 
"  small  rounds  "  and  the  cuttings  commonly  known  as  English  "  stick  " 
rhubarb  are  obtained  from  the  side  branches  of  the  root.  Some  of  the 
flat  pieces,  except  for  their  shrunken  exterior,  are  not  unlike  the  East 
India  rhubarb  of  commerce,  and  being  more  thoroughly  dried  right 
through  and  harder  in  the  centre  seem  to  meet  with  a  greater  demand 
than  the  rounds.  The  raspings  obtained  in  trimming  the  pieces  are 
ground  into  powder.  The  average  yield  of  the  dried  root  every  year 
is  from  eight  to  ten  tons. 
Of  the  Rheum  officinale,  Mr.  Usher  has  now  under  cultivation  in  his 
garden  about  forty  large  plants  between  two  and  three  years  old,  as 
well  as  about  200  seedlings.  These  plants  are  truly  magnificent,  each 
plant  occupying  a  space  from  eight  to  twelve  feet  square,  and  standing 
four  or  five  feet  high.  Some  of  the  leaves  are  nearly  three  feet  broad, 
and  longer  than  they  are  broad.  It  is  just  suitable  as  an  ornamental 
plant  for  lawns,  where  it  would  have  plenty  of  room  to  grow.  Indeed 
it  is  already  used  in  this  way  in  some  of  the  public  gradens  in  Paris. 
The  root  of  only  one  plant  has  as  yet  been  dried,  and  was  obtained 
from  a  plant  barely  two  years  old.  A  piece  of  this  root  has  been  pre- 
sented to  the  museum  of  the  Pharmaceutical  Society,  the  remaining 
having  been  almost  all  sent  to  the  Philadelphia  Exhibition,  where  it 
obtained  a  medal,  and  was  purchased. 
In  color,  the  dried  root  is  paler,  although  the  veins  are  darker,  than 
in  the  East  Indian  rhubarb.  Mr.  Usher  informs  me  that  it  neverthe- 
less yield  a  bright  yellow  powder.  The  external  markings  do  not 
exactly  correspond  with  those  of  the  East  India  rhubarb,  the  peculiar 
reticulated  appearance  characteristic  of  that  sort  not  being  visible  on 
the  two  pieces  that  I  have  seen.    This  may,  however,  be  due  to  the 
