^mAp?i!ri8P84arm'}        Pipitzahoic  Acid  and  Species  of  Perezia.  185 
ON  THE  PRESENCE  OF  PIPITZAHOIC  ACID 
IN  THE  PEREZIAS  FOUND  IN  THE  TERR  [TORY  OF  THE  UNITED  STATES, 
AND  ON  THE  GEOGRAPHICAL,  DISTRIBUTION  OF  THE  NORTH 
AMERICAN  SPECIES  OF  THAT  GENUS. 
By  Charles  Mohr,  Mobile,  Ala. 
Translated  by  the  Author  from  Pharmaceulische  Rundshau. 
The  remarks  on  pipitzahoic  acid  which  appeared  in  the  "  Rund- 
schau "  of  November  has  directed  the  attention  of  the  writer  anew  to 
a  subject  in  which  he  felt  himself  greatly  interested  during  his  stay  in 
Mexico  in  1857,  where  he  got  acquainted  with  the  publication  of  the 
researches  of  Rio  de  la  Lozas,  announcing  his  discovery  of  this  pecu- 
liar organic  acid,  made  a  short  time  before.  The  inquiries  after  its 
source,  the  "Baiz  del  Pipitzahuac"  made  in  consequence  at  the  time  in 
the  leading  drug  houses  of  the  city  of  Vera  Cruz  and  at  Orizava  were 
leading  to  no  results.  Amongst  the  varied  stock  of  the  numerous 
drugs  derived  from  Mexican  plants  no  root  was  found  of  that  name, 
and  only  a  single  species  of  Perezia  was  encountered  during  the  fre- 
quent botanical  excursions  made  in  these  parts  of  the  Mexican  republic, 
also  the  only  one  found  amongst  the  large  collection  made  by  the  bota- 
nist Bolteri,  of  Orizava.  After  a  lapse  of  many  years  the  determina- 
tion of  this  plant  was  only  made  possible  a  few  weeks  ago,  since  the 
review  of  the  North  American  Perezias  by  Prof.  Gray  has  come  to 
hand,  where  it  is  described  under  the  name  of  Perezia  Dngesii.1 
These  plants  seem  to  shun  the  damp  clime  of  the  eastern  declivity 
of  the  Mexican  Andes;  they  are  rather  plants  of  the  desert  regions, 
finding  their  proper  home,  with  the  widest  distribution,  in  the  rainless, 
arid  plains  (mesas),  and  on  the  rocky  hills  of  the  highlands  of  northern 
Mexico  and  the  adjoining  parts  of  the  United  States. 
The  genus  Perezia,  Lag.,  as  defined  by  Gray,2  embraces  bilabiate 
composite  of  the  sub-order  Labiatiflorre  and  the  tribe  Mutisiacea?,  with 
perfect  and  throughout  homogeneous  flowers,  united  to  a  greater  or 
lesser  number  in  heads  with  a  naked  receptacle,  surrounded  by  a 
campanulate  or  top-shaped  involucrum  of  stiff  elongated  more  or  less 
lanceolate  scales,  imbricated  in  two  or  more  rows.    Corolla  with  a 
>Gray,  "Proceed.  Am.  Acad.  Arts  and  Sciences,''  vol.  xix,  Oct.,  1883. 
'JGray,  loc.  cit.,  and  Botany  of  California,  vol.  1. 
