Am.  Jour.  Pharm. ) 
October,  1920.  j 
Rhus  Venenata  DC. 
695 
RHUS  VENENATA  DC. 
By  H^ber  W.  Youngken,  Ph.D.,  and  George  A.  S1.0THOWER,  B.Sc.  B.A.P. 
PHII^ADELPHIA,  PA. 
Five  poisonous  species  of  Rhus  plants  are  common  to  the  United 
States  and  Canada,  namely:  Rhus  toxicodendron  Rhus  venenata 
DC,  Rhus  diver siloha  Torr.  and  Gray,  Rhus  succedanea  L,  and  Rhus 
vernicifera  DC. 
Commercially,  Rhus  vernicifera,  Rhus  succedanea,  and  to  some 
extent,  Rhus  venenata,  yield  a  lac  which  is  of  value  in  the  making 
of  the  famous  Japan  varnishes. 
Rhus  toxicodendron  was  official  in  the  sixth  and  seventh  editions 
of  the  U.  S.  P.  Its  use  in  medicine  at  the  present  time  is  in  the  main 
limited  to  the  practice  of  homeopathy,  where  it  is  used  in  nervous 
disorders  and  dermatotherapy.  Rost  and  Gilg^  make  mention  of 
it  as  having  been  used  in  the  treatment  of  cancer. 
There  are  probably  no  other  plants  in  existence  which  cause  as 
much  human  distress  and  suffering  as  Rhus  toxicodendron  and  Rhus 
venenata. 
Many  substances  are  referred  to  in  the  literature  as  causing 
the  dermatitis  produced  by  these  plants.  They  include  a  vapor, 
gas,  volatile  alkaloid,  volatile  acid,  infection  by  bacteria,  glucoside, 
non- volatile  acid,  resin,  polyhydric  phenol  and  a  non- volatile  oil. 
That  the  poisonous  substance  was  a  non- volatile  oil,  which  resini- 
fies  on  exposure  to  the  atmopshere,  was  discovered  by  Pfaff^  who 
found  it  to  exist  in  all  parts  of  the  plant. 
As  to  how  this  non-volatile  oil  comes  in  contact  with  individuals, 
the  consensus  of  opinion  seems  to  be  that  the  winds  and  domestic 
animals  carry  the  pollen  grains  and  hairs.  Pfaff  and  Schwalbe^ 
found  the  pollen  grains  and  hairs  to  contain  the  poisonous  substance. 
On  the  other  hand,  Rost  and  Gilg,^  in  a  very  extensive  work,  were 
unable  to  find  the  poison  in  the  hairs  and  pollen  from  these  plants. 
In  this  investigation  we  shall  undertake  to  inquire  into  the  his- 
tological nature  of  the  stems  and  leaves  of  Rhus  venenata  and  make 
observations  on  its  poisonous  constituent. 
The  specimens  used  in  this  work  were  collected  near  Atco,  New 
Jersey,  in  July  of  19 19,  and  allowed  to  dry.  The  Martindale  Herba- 
rium of  the  Philadelphia  College  of  Pharmacy  and  Science  was  con- 
sulted and  proved  of  considerable  value. 
