170 
Parthenium  Hysterophorous. 
Am.  Jour.  Pharm. 
April,  1897. 
Its  heads  are  loosely  panicled  with  involucre  of  five  ovate  scales, 
arranged  in  two  rows,  (Fig.  1).  There  are  in  each  head  five  ray 
florets  in  a  single  row,  each  resting  within  an  oval  chaffy  scale  which 
is  hairy  above,  and  which,  on  separating,  usually  divide  in  three 
portions.  The  ray  florets  are  short,  pistillate,  ripening  to  smooth, 
compressed  achenia,  with  pappus  composed  of  oval  scales  {Fig.  2). 
The  disc  florets  are  tubular,  five-toothed  and  sterile,  having  syn- 
genesious  anthers  producing  pollen  grains,  which  are  prickled  simi- 
larly to  those  of  malva.  Those  nearest  the  ray  florets  are  attached  in 
pairs  to  each  of  the  chaffy  scales  mentioned  above  [Fig.  3).  Each 
Fig.  1.  Parthenium  Hysterophorous.  Outer  involucre,  magnified  twenty 
diameters. 
inner  floret  has  its  own  chaffy  scale,  which  is  more  narrow  than 
those  on  the  outer  rim.  The  receptacle  is  conical  and  not  very 
prominent. 
The  plant  commonly  called  Bastard  Feverfew  grows  in  the  West 
Indies  (where  it  is  known  as  Escoba  amargo),  in  Florida  and  in 
Louisiana.  It  has  been  introduced  in  Europe  as  Absinthe  sauvage 
des  Antilles.  It  attains  the  height  of  three  feet,  possesses  a  peculiar 
heavy  odor,  while  the  leaves  and  flowers  have  an  intensely  bitter 
taste. 
The  anatomy  of  the  active  part  of  Parthenium  hysterophorous  is 
simple.    The  chaff  is  composed  of  longitudinally  elongated  cells  in 
