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. About 3 per cent, of glycyrrhizin, a crys- 

 talline, intensely sweet substance consisting of the calcium and 

 potassium salts of glycyrrhizinic acid, which latter is an ester of 

 glycyrrhetinic acid; 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 in crystal fibers. 



Allied Plants. The root of wild or American licorice, 

 Glycyrrhi::a lepidota, a perennial herb indigenous to Western 

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

 tains 6 per cent, of glycyrrhizin and considerable glycyramarin. 



A number of plants of this family contain principles similar 

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

 licorice (Abriis prccatoriiis) of India and the West Indies; the 

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

 species oi Ononis as well; the locust (Robinia Psendacacia) of 

 the United States and Canada ; Caragana pygniora of Siberia and 

 Northern China; Hedysaruui auicricanuui of the Northern 

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

 of Brazil and Paraguay ; the rhizome of Polypodium vulgare 

 (Filices). (See also Galium, p. 382.) 



The root of G. uralcnsis of Siberia is said to be only slightly 

 inferior to the best kind of Russian licorice. 



RHEUM. RHUBARB. The rhizome of Rheum oiUciuale, 

 Rheum pahnatiim, Rheum paluiafum tanguficuni. and probably 

 other species of Rheum (Fam. Polygonacess), 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 vears old, most of the bark is removed, and thev are then 



