238 - RHIZOMES AND ROOTS. 



(114) Ipecacuanha Root. 



The root of Psychotria Ipecacuanha, Stokes (N.O. Rubiacese). 

 The root presents the following structure : 



(1) Cork, composed of several rows of very narrow tangentially 

 elongated cells which, in surface view are polygonal and 

 isodiametric. 



(2) Cortex, which is very largely developed and consists of 

 tangentially elongated cells, most of which contain starch, but 

 a few are filled with acicular crystals of calcium oxalate. 



The starch grains are either simple or compound ; the former 

 are oval or rounded, the latter are composed of from two to 

 five constituent grains, each of which usually exhibits one 

 rounded surface and one or more flat ones. The single grains 

 occasionally reach 12^4 in length but never exceed 15/u. 



The cells of the cortex diminish in size as they approach the 



(3) Bast Ring, in which there are groups of sieve tissue but no 

 bast fibres. 



(4) Wood, composed of tracheids, wood fibres and wood 

 parenchyma. It is remarkable for the absence of vessels. The 

 - a cheids have moderately thick walls, very distinct areolated 

 pits, and often near the pointed extremities a large perforation, 

 which is not always easy to see. 



The diagnostic characters of powdered ipecacuanha are : 



(a) The starch grains. 



(b) The acicular crystals of calcium oxalate. 



(c) The absence of vessels, presence of perforated 



tracheids. 



(d) The absence of sclcrenchymatous cells or bast fibres. 



