404 
Rhus  Glabra  and  Rhus  Typhina.      I Am-  Jour  -pharra- 
Jt  \  September,  1913. 
nearly  colorless,  the  glandular  hairs  only  having  the  colored  sap 
and  these  possess  it  in  the  cells  comprising  the  upper  or  head  portion. 
Rhus  Glabra  Borealis. 
In  a  footnote  in  his  "  Silva  of  North  America, "  Sargent 3  states : 
"  Individual  plants  almost  intermediate  in  character  between  Rhus 
typhina  and  Rhus  glabra  are  occasionally  found,  indicating  the  possi- 
bility of  natural  hybrids  between  the  two  species.''  In  the  New  York 
Botanical  Garden  Dr.  Britton  has  labeled  a  number  of  specimens, 
Rhus  glabra  borealis.  I  have  not  examined  these  plants  closely  but 
have  made  a  microscopical  study  of  the  hairs  from  several  of  the 
fruits  of  this  material.  The  hairs  are  very  characteristic  and  seem 
to  be  intermediate  between  those  of  Rhus  glabra  and  those  of  Rhus 
typhina  (Fig.  i,  b).  We  find  the  characteristic  spatulate  hairs  of 
Rhus  glabra  only  they  are  much  larger  and  as  a  whole  much  nar- 
rower, the  upper  portion  tends  to  become  obtuse  and  even  acute 
rather  than  rounded.  Again  in  certain  specimens  the  hairs  are 
very  long  and  narrow  resembling  those  of  Rhus  typhina.  In  a  gen- 
eral way  we  can  say  the  non-glandular  hairs  of  Rhus  glabra  borealis 
vary  from  elongate-spatulate  and  narrow  cylindrical  to  needle- 
shaped  and  are  from  100  microns  to  i  mm.  in  length.  They  are 
frequently  cylindrical  at  the  base  and  needle-shaped  in  the  upper 
portion,  or  they  may  be  spatulate  in  the  upper  portion  and  cylindrical 
below,  and  again  they  will  have  a  needle-shaped  base  and  summit 
and  be  constricted  in  the  middle.  They  are  more  or  less  septate  and 
in  this  also  they  resemble  the  hairs  of  Rhus  glabra.  These  hairs 
also  contain  a  pink  or  bright  crimson  cell  sap  which  in  permanency 
resemble  Rhus  glabra  rather  than  Rhus  typhina.  Associated  with 
these  non-glandular  hairs  occur  the  small,  glandular  hairs  similar  to 
those  which  have  been  referred  to  under  both  Rhus  glabra  and 
Rhus  typhina.  In  size  these  latter  seem  to  be  intermediate  with 
those  found  on  Rhus  typhina  and  Rhus  glabra.  While  these  observa- 
tions have  no  practical  significance  in  the  study  of  the  drug,  as  the 
fruits  are  not  found  in  the  commercial  article,  they  will  doubtless 
prove  of  some  botanical  interest,  as  in  the  study  of  the  hairs  of  the 
two  species  and  their  varieties  we  have  a  very  simple  means  appar- 
ently of  determining  the  extent  to  which  hybridization  may  have 
taken  place. 
