Am.  Jour.  Pharm.  \ 
November,  1910.  j 
Rhus  Michauxii. 
503 
Shortly  after  this  Gray  and  Robinson  19  reviewed  portions  of 
the  evidence  in  the  case  both  pro  and  con,  but  arrived  at  no 
conclusions. 
From  the  foregoing  it  can  be  seen  that  the  recorded  evidence 
favorable  to  the  theory  that  R.  Michauxii  is  poisonous  is  meagre 
and  is  largely  of  the  "  hearsay  "  variety.  A  critical  examination  of 
the  evidence  shows  that  but  one  authority  (  Sargent)  has  added 
anything  from  personal  observation  to  strengthen  the  theory,  while 
two  others  (Curtis  and  Ashe)  have  each  declared  their  opinion  to 
the  contrary. 
From  a  study  of  the  botanical  literature  of  Rhus  species  and 
from  an  examination  of  the  fruit  of  several  toxic  and  non-toxic 
species,  the  author,  several  years  since,  became  convinced  that  Rhus 
Michauxii  could  not  be  poisonous.  In  correspondence  with  Pro- 
fessor Wm.  Trelease,  Director  of  the  Missouri  Botanical  Garden, 
it  was  learned  that  this  noted  botanist  had  arrived  at  the  same  con- 
clusion.   Professor  Trelease  says : 
"  Outside  of  the  Toxicodendron  group,  with  the  aberrant  leaf- 
scars,  buds,  and  fruits,  I  have  always  been  somewhat  suspicious  as 
to  the  poisonous  properties  of  sumacs  (  naturally  without  failing  to 
give  heed  at  least  to  a  current  belief  in  the  poisonousness  of  other 
species).  For  this  reason,  when  I  began  to  grow  R.  Michauxii, 
ten  or  fifteen  years  ago,  I  took  occasion  to  rub  its  crushed  leaves 
over  my  hand  and  I  have  several  times  since  repeated  the  trial 
without  ever  suffering  the  least  poisoning,  although  I  am  moderately 
susceptible  to  the  poison  ivy,  and  I  am  consequently  inclined  to  think 
that  this  species  is  poisonous  to  only  very  susceptible  individuals,  if 
to  any  one." 
In  a  later  communication  he  writes : 
"  It  is  .  .  .  one  of  the  red-fruited  sumacs  differing  almost 
genetically  from  the  white-fruited  poisonous  species." 
In  response  to  an  inquiry  as  to  whether  the  juice  of  this  species 
darkens  on  exposure  to  the  atmosphere  (as  Sargent  had  stated)  he 
replied : 
"  The  observation  now  made  is  that  the  nearly  colorless  sap 
does  not  darken  as  the  lacquer  varnishes  do." 
In  addition  to  making  observations  at  the  request  of  the  author 
concerning  the  plant  and  its  visitors,  Professor  Trelease  kindly 
Gray  and  Robinson:  Syn.  Flor.  N.  Am,  i,  II,  384  (1895-7). 
