322 
False  and  True  Senega. 
j  Am.  Jour.  Pliarm. 
\       July,  1881. 
tho  characteristic  keel-like  projection  and  the  irregularly  formed 
A^oody  tissue. 
The  true  senega  is  of  from  a  light  to  a  dark  brown  coloi%  sur- 
mounted by  a  very  knotty  head  or  crown  of  from  a  half  to  one  and  a 
quarter  inch  in  diameter.  The  root  proper  is  of  from  one-eighth  to 
three-eigliths  inch  in  diameter  at  the  upper  part,  is  branched  and 
tapering,  of  from  two  to  five  inches  in  length,  and  very  much  con- 
torted, with  a  projecting,  keel-like  ridge,  running  the  entire  length  of 
the  root  and  rootlets  in  a  spiral  form.  It  is  both  longitudinally  and 
transv^ersely  wrinkled,  breaks  with  a  short  fracture,  and  exhibits  a 
somewhat  porous,  rather  firmly  adhering  bark,  which  varies  in  thick- 
ness of  from  one-third  to  one-fifth  of  the  thickness  of  the  root.  The 
projecting  keel  disappears  upon  being  boiled  with  water,  and  reap- 
pears when  the  root  is  dried.  The  woody  portion  is  from  a  light  yel- 
low to  almost  a  white  color,  and  is  in  different  places  very  irregular  in 
shape,  owing  to  a  non-formation  of  portions  of  the  woody  tissue. 
The  root  is  capable  of  being  reduced  to  fine  powder  with  greater 
ease  than  the  false  variety,  the  dust  being  very  sternutatory ;  when 
chewed  it  produces  a  painful  sensation  in  the  throat  and  excites 
conghing. 
False  Senega  Root.— Transverse  and  longitadinal  section  to  center 
The  false  senega,  when  cut  transversely,  exhibits  an  outer  layer  of 
cells,  rather  irregular,  very  compact,  thin  and  corky;  the  inner  bark 
is  about  five  or  six  times  as  thick,  its  cells  are  very  regular  and  appear 
in  distinct  circles,  varying  in  size ;  the  outer  circle  is  formed  of  very 
small,  flattened  cells;  the  second,  broader  layer,  consists  of  oval  cells, 
and  is  followed  by  a  zone  of  smaller  slightly  flattened  cells,  and  by  an 
inner  circle  of  cells,  nearly  similar  to  the  preceding.  A  very  thin 
cambium  layer  separates  the  bark  from  the  wood,  which  is  rather 
