520 
Distribution  of  Tannin  Plants. 
("Am.  Jour.  Pharm. 
\  November,  1913. 
Occasionally  there  seems  to  be  a  gradual  variation  in  tannin  content 
between  closely  related  families.  Some  natural  orders  contain  no 
families  of  plants  at  present  known  to  produce  tannin,  and  in  other 
orders  almost  the  entire  range  of  families  furnish  plants  containing 
tannin  but  in  very  limited  quantities.  From  the  information  which 
is  at  present  available  it  does  not  seem  possible  to  establish  any  very 
direct  correlation  between  the  production  of  tannin  by  different  fami- 
lies of  plants  and  their  relationship  to  any  of  the  schemes  of  classifi- 
cation which  are  in  use  by  modern  botanists.  Since,  however,  most 
of  the  known  facts  concerning  the  distribution  and  abundance  of 
plants  have  been  collected  and  arranged  with  reference  to  the  botani- 
cal classification  it  will  be  desirable  to  recognize  the  usual  divisions 
into  orders  and  families  for  the  purpose  of  more  clearly  setting  forth 
the  general  facts  concerning  the  geographical  distribution  of  plants 
producing  tannin. 
Turning  now  to  the  actual  question  of  geographical  distribution 
of  plants  producing  tannin,  we  may  at  once  dismiss  from  considera- 
tion all  of  those  families  in  the  previously  mentioned  classification 
other  than  the  seed-plants.  We  will  consider  for  convenience  of  dis- 
cussion each  of  the  three  main  groups  of  seed-plants,  beginning  with 
the  Gymnosperms.  In  this  subdivision  practically  all  of  the  plants 
known  to  contain  tannin  occur  in  one  of  four  natural  orders,  the 
chief  of  which  is  the  Pinacese,  to  which  belong  the  pines,  spruces, 
hemlocks  and  firs.  The  distribution  of  this  group  in  the  northern 
hemisphere  naturally  follows  closely  that  of  the  coniferous  forests 
and  aside  from  the  occurrence  of  a  species  of  Podocarpus,  in  Southern 
Africa,  and  a  species  of  Phyllocladas  in  Tasmania  and  New  Zealand, 
there  are  no  important  tannin-bearing  representatives  of  the  Gymno- 
sperms to  be  found  south  of  the  Equator.  The  distribution  in  the 
Northern  Hemisphere  coincides  in  a  more  or  less  general  way  with 
the  principal  mountain  ranges,  the  slopes  of  which  are  naturally 
wooded  with  forests  of  coniferous  trees.  This  of  course  tells  nothing 
of  the  distribution  in  detail  but  merely  indicates  the  densest  areas 
on  which  plants  of  this  group,  having  a  high  tannin  content,  may  be 
found.  Scattered  generally  throughout  certain  sections  of  the  United 
States  and  Mexico,  as  well  as  through  regions  in  Central  and  North- 
ern Europe  and  Asia,  are  many  tannin-bearing  species  which  belong 
to  this  group,  but  since  by  far  the  largest  number  of  important  species 
are  included  among  either  the  pines,  hemlocks  or  spruces,  it  follows 
that  the  general  distribution  of  this  group  of  tannin  plants  conforms 
