230 KHIZOMES AND ROOTS. 



(110) Gentian Root. 



The root of Gentiana lutea, Linn. (N.O. Gentianaceae). 

 The commercial drug consists of rhizome as well as root. 

 The root presents the following structure : 



(1) Corky consisting of several rows of tabular cells which in 

 surface view are polygonal and have slightly wavy walls. 



(2) Collenchyma, the cells of which are rounded, have rather 

 thick walls and contain an amorphous substance, very minute 

 crystals, and small oily globules. 



(3) Cortical Parenchyma, very narrow and composed of tan- 

 gentially elongated polygonal cells, each of which contains 

 a distinct nucleus and minute crystals, the latter being often 

 collected in one of the angles of the cell. There is no 

 sclerenchyma in the cortex. 



(4) Bast Ring, the cells of which are small ; it contains 

 scattered groups of sieve tissue. 



(5) Wood, consisting principally of parenchymatous tissue and 

 traversed by medullary rays seven or eight cells wide. The 

 vessels are scattered and isolated or in small groups ; the wood 

 parenchyma is not lignified, and closely resembles that of the 

 bast ring, the cells containing minute crystals and oily globules. 

 The root contains at most an occasional small starch grain. 



The diagnostic characters of powdered gentian root are : 



(a) The absence of starch. 



(b) The presence of minute crystals and oily globules. 



(c) The brownish colour. 



(d) The large reticulated or scalariform vessels. 



(e) Absence of sclerenchymatous cells or fibres. 



