Am.  Jour.  Pharm. 
December,  1906. 
}    Root- Structure  of  Spigelia  Marilandica. 
557 
The  root- structure  of  Ruellia,  when  examined  under  the  micro- 
scope, is  widely  different  from  that  of  Spigelia,  but  the  rhizome,  at 
least  its  external  structure,  resembles  that  of  Spigelia  much  more 
than  any  species  of  Phlox  ;  to  the  non-critical  examiner  the  rhizomes 
of  Ruellia  may  easily  be  taken  for  true  Spigelia.  In  order  to  guard 
against  any  such  mistake  the  following  points  may  be  recorded. 
Fig.  i  represents  a  mature  rhizome  of  Ruellia  ciliosa,  Pursh,  more 
than  seven  years  old.  The  lower  portion  of  this  rhizome  shows  a 
more  condensed  growth  and  shorter  internodes  than  the  upper  part, 
which  is  almost  vertical  and  of  which  the  internodes  are  stretched. 
Fig.  4.  Fig.  5. 
Fig.  4.  Longitudinal  section  of  the  same  root,  showing  a  cystolithe.  X  480. 
Fig.  5.  Transverse  section  of  another  root,  but  of  the  same  species,  show- 
ing the  cortex  (C.)  with  a  cystolithe,  the  endodermis  (End.),  the  pericam- 
bium  (Camb. )  and  the  leptome  with  a  cell  containing  a  raphidine  (R.)  and 
some  stereomatic  cells  (St.).    X  480. 
Such  difference  in  growth  is  commonly  to  be  observed  in  Ruellia. 
The  basal  part  of  the  aerial  shoots  remain  attached,  as  may  be  seen 
from  the  figure,  thus  the  cup-shaped  scars  so  characteristic  of  Spigelia 
are  absent.  The  roots  are  long,  sparingly  branched,  and  generally 
coarser  than  those  of  Spigelia.  If  we  now  examine  the  internal 
structure  of  the  Ruellia  rhizome,  we  notice  at  once  the  abundance 
of  cystolithes  in  the  cortex  and  pith,  while  these  are  totally  absent 
from  the  rhizome  of  Spigelia. 
