244 RHIZOMES AND ROOTS. 



(117) Liquorice Root. 



The root and subterranean stem of Glycyrrhiza glabra, Linn. 

 (N.O. Leguminosae). 



The root presents the following structure : 



(1) Cork, the cells of which are brown in colour and flat- 

 tened; in surface view they are polygonal and isodiametric, 

 their walls are slightly thickened and wavy in outline. 



(2) Cortex, composed of tangentially elongated polygonal cells 

 with intercellular spaces. The cells arc filled with small simple 

 starch grains. This tissue does not contain any sclerenchyma- 

 tous cells, but near the periphery there are numerous cells 

 containing prismatic or rhombohedral crystals of calcium 

 oxalate. 



(3) Bast Ring, characterised by the presence of numerous bun- 

 dles of bast fibres arranged in c ncentric circles. Each bundle 

 consists of a number of fibres with very strongly thickened 

 walls, and is surrounded by small cells containing crystals of 

 ca'cium oxalate. The bast consists of bast parenchyma 

 traversed by numerous groups of sieve tissue, many of which 

 are nearly obliterated. 



(4) Wood, divided into wood bundles by medullary rays three 

 or four cells wide. The wood bundles consist of vessels of varying 

 size, bub often wide (lOO^u), wood parenchyma and wood fibres, 

 the latter closely resembling the bast fibres and like these 

 accompanied by calcium oxalate crystals. 



The diagnostic characters of powdered liquorice root are : 



(a) The abundant, very thick-walled, grouped, yellowish 



bast fibres. 



(b) The abundant calcium oxalate crystals. 



(c) The s nail starch grains. 



(d) The characteristic vessels, especially the larger. 



