156 
Ballota  Hirsuta. 
Am.  Jour.  Pharm. 
March,  1919. 
lar  to  that  of  the  foliage  leaf,  but  on  a  reduced  scale.  The  tendency 
for  more  of  the  branched  hairs  to  show  the  central  branch  glandular 
has  been  observed. 
The  chief  practical  diagnostic  differences  between  Ballota  hirsuta 
and  Marrubium  vulgar e  are  as  follows: 
1.  The  calyx,  which  in  Ballota  hirsuta  is  densely  hairy,  distinctly 
bi-labiate-infundibuliform  with  limb  margin  showing  10  broadly 
acute  or  mucronate  teeth,  whereas  in  Marrubium  vulgare  it  is 
sparsely  hairy,  distinctly  tubular  with  ten  bristle-like  recurved  teeth. 
2.  The  absence  in  Marrubium  vulgare  and  presence  in  Ballota 
hirsuta  of  certain  branched  trichomes,  the  central  branch  of  which 
bears  a  glandular  head  or  one  of  two  to  four  cells. 
Fig.  9.  Various  types  of  glandular  trichomes  found  on  the  calyx  and 
foliage  leaf  of  Ballota  hirsuta.  a,  lateral  vi-ew,  and  b,  view  from  above  of 
the  balloon  type  of  glandular  trichome  showing  (in  a)  a  short  unicellular 
stalk  and  (in  b)  a  four-celled  glandular  head;  c,  d,  e,  f,  other  types  of 
glandular  hairs  having  a  1-2-celled  stalk  and  a  1-2-celled  glandular  head. 
(All  highly  magnified.) 
3.  The  branched  trichomes  of  Ballota  hirsuta  show  on  the  aver- 
age longer  basal  stalks,  thicker  walls  and  more  rigid  branches  than 
those  of  Marrubium  vulgare. 
4.  A  number  of  trichomes  of  Ballota  hirsuta  are  lignified  at  their 
bases,  whereas  in  Marrubium  vulgare  no  such  lignification  has  been 
observed. 
Pharmacognosy  Research  Laboratory, 
Philadelphia  College  of  Pharmacy. 
LITERATURE. 
Bentham.   Labiatarum  Genera  et  Species,  p.  595. 
Solereder.    Systematic  Anatomy  of  the  Dicotyledons,  vol.  1,  pp.  637,  639. 
