Am.  Jour.  Pharm.  \ 
October,  19 19.  * 
Triticum  Repens. 
685 
TRITICUM  REPEXS:  A  COMMERCIAL  RARITY.1 
By  James  Small,  D.Sc.  Ph.C.  F.L.S. 
Some  time  ago  Mr.  E.  M.  Holmes  informed  me  that  there  was  a 
scarcity  of  genuine  couch  grass  in  commerce,  and  suggested  that  a 
microscopic  investigation  of  the  material  being  sold  as  Triticum 
repens  would  be  of  interest,  the  principal  point  being  the  identifica- 
tion of  the  botanical  source  of  the  commercial  product.  At  his 
request  I  examined  properly  authenticated  material  of  various 
species  of  grasses,  and  also  a  number  of  commercial  samples.  The 
result  of  this  investigation  is  summarized  in  the  title.  Triticum 
repens  is  a  commercial  rarity,  and  the  chief  ,  if  not  the  only,  substi- 
tute is  the  rhizome  of  Cynodon  Dactylon,  the  dog  grass. 
The  method  of  examination  was  simple.  Transverse  sections  of 
pieces  from  each  authentic  sample  were  prepared  and  double- 
stained  with  methylene  blue  and  erythrosin.  Similar  unstained  sec- 
tions were  prepared  from  the  commercial  samples,  and  a  comparison 
was  made.  The  rhizomes  all  have  the  usual  scattered  vascular 
bundles,  with  a  few  large  vessels.  They  also  agree  in  having  a  cer- 
tain amount  of  sclerenchyma,  and  it  is  particularly  by  the  amount 
and  distribution  of  this  tissue  that  the  different  species  can  be 
identified. 
Description. 
Triticum  repens. — There  are  two  rings  of  sclerenchyma.  an 
outer  ring,  three  or  four  cells  wide,  forming  a  hypodermis  and 
a  broader  ring  forming  a  common  sheath  to  the  vascular  bundles, 
and  at  the  same  time  completely  enclosing  the  outer  bundles  (Fig.  i). 
A  few  small  bundles  occur  in  the  cortex  surrounded  by  a  single  row 
of  sclerenchymatous  cells.  In  mature  rhizomes  the  pith  shows  some 
•disintegration,  and  the  center  of  the  section  is  hollow. 
Cynodon  Dactylon. — Only  one  ring  of  sclerenchyma  is  present, 
forming  a  wavy  band  inside  the  narrow  cortex  and  around  the  outer 
part  of  the  rhizome.  The  cortex  in  this  case  is  narrower  than  in 
Triticum  repens,  and  it  encloses  no  small  vascular  bundles.  The 
scattered  bundles  within  the  ring  of  sclerenchyma  have  each  a  bundle 
sheath  of  the  same  tissue  one  or  two  cells  wide.   Dog  grass  rhizome 
1  Reprinted  from  The  Pharmaceutical  Journal  and  Pharmacist.  July  26, 
1919. 
