474 BOTANY .AND PHARMACOGNOSY. 



Inner Structure. — See Figs. 104; 204; 282, B. 



Russian Licorice. — Nearly cylindrical, tapering, sometimes 

 split longitudinally, 15 to 30 cm. long, 10 to 30 mm. in diameter; 

 externally lemon-yellow, nearly smooth, porous, with detachable 

 bast fibers and circular rootlet-scars, cork, if present, more or less 

 easily detachable ; internally lemon-yellow, bark coarsely fibrous, 

 wood radially cleft, not so fibrous as the Spanish variety. 



Constituents. — A glucoside glycyrrhizin (ammonium salt of 

 glycyrrhizic acid) from 2.5 to 6 per cfent. (Russian licorice is said 

 to contain as much as 7.5 per cent.J, to which the drug owes 

 its characteristic taste; asparagin 2 to 4 per cent, (see Althaea) ; 

 a bitter principle glycyramarin, which occurs principally in the 

 bark and hence is less abundant in the Russian licorice ; a volatile 

 oil 0.03 per cent. ; mannit ; considerable starch and calcium oxal- 

 ate chiefly as crystal fibers. 



Allied Plants. — The root of wild or American licorice, 

 Glycyrrhiza lepidota, a perennial herb indigenous to Western 

 North America, is somewhat similar to Spanish licorice. It con- 

 tains about 6 per cent, of glycyrrhizin and considerable glycyra- 

 marin. 



A number of plants of this family contain principles similar 

 to glycyrrhizin, as the root and leaves of Indian or Jamaica 

 licorice (Abrtts precatorius) of India and the West Indies; the 

 root of Ononis spinosa, a perennial herb of Europe, and other 

 species of Ononis as well; the locust (Robinia Pseudacacia) of 

 the United States and Canada ; Caragana pygmcsa of Siberia and 

 Northern China ; Hedysarum americanum of the Northern 

 United States and Canada ; Periandra mediterranea, and P. dulcis 

 of Brazil and Paraguay. (See also Galium, p. 382.) 



A principle resembling glycyrrhizin has also been obtained 

 from the rhizome of Poly podium milgare (Filices). 



RHEUM.— RHUBARB.— The rhizome of Rheum oMcimle, 

 Rheum palmatuin. Rheum palmatum tanguticimi, and probably 

 other species of Rheum (Fam. Polygonaceae), perennial herbs 

 ( Fig. 205 ) indigenous to Northwestern China and Eastern Thibet, 

 and sparingly cultivated in other parts of the world (p. 262). 

 The rhizomes are collected in autumn from plants that are eight 

 to ten years old, most of-the bark is removed, and they are, then 



