RHEUM 155 



SOURCE. Rhubarb is obtained from many species of Rheum, mostly 

 natives of Asia, especially of China, Chinese Tartary, and Thibet. 

 Russian or Turkish rhubarb so called because all of it imported into 

 these countries from China had to be submitted to official inspection 

 is now never found in the market. The caravan commerce between 

 Russia and China has been an important one for many generations, 

 and the rhubarb in European commerce was almost entirely carried 

 from China through Persia and Asia Minor; hence the old name of 

 Turkey rhubarb. Later on it was brought through Northern China, 

 Siberia, -and European Russia (Kiachta) to St. Petersburg. 



The "Russian rhubarb" of early times was evidently what is now 

 known as Shensi variety. That brought into the trade by the port of 

 Canton, known in Europe as Indian rhubarb, is now called Canton. 

 The Chinese rhubarb is the variety recognized in commerce. The 

 root, often attaining a weight of fifty pounds, is cut up into pieces of 

 a suitable size for drying, holes being usually bored through the pieces 

 and a string passed through for hanging them up. 



DESCRIPTION OF DRUG. In cylindrical, conical, or plano-convex pieces, 

 or pieces with no regular shape, varying in size from 75 to 150 mm. 

 (3 to 6 in.) long, and 50 to 75 mm. (2 to 3 in.) thick; they are usually 

 sorted into "round" and "flat" rhubarb. Externally somewhat 

 shriveled, often with portions of the cortical layer which have not 

 been pared away; usually covered with a bright yellow dust, beneath 

 which it is seen to have a rusty-brown hue; under the lens it is seen 

 to be marked with the medullary rays (innumerable short, broken 

 lines of a deep brown color) crossing a white ground, forming elon- 

 gated whitish meshes. Well-formed pieces broken transversely dis- 

 play near the cambium zone dark lines arranged as an internal ring 

 of star-like spots, with radiating, reddish medullary rays, marking 

 the internal origin of the leaves. The tissue is made up of a white 

 parenchyma, with reddish-brown or brownish-yellow medullary rays, 

 so twisted, however, as to be scarcely recognizable as such, giving a 

 cross-section a mottled appearance of red, white, and yellow. The 

 white parenchyma cells are loaded with starch and crystals of calcium 

 oxalate, which- cause the grittiness between the teeth; the medul- 

 'lary rays contain the active constituents. Odor characteristics; taste 

 bitter, aromatic, astringent, and gritty. When chewed, it tinges 

 the saliva orange-yellow. It yields a yellowish powder with a reddish- 

 brown tinge. 



The common pie-plant, Crimean rhubarb, from Rheum rhapon- 

 ticum Linne, is a European variety, having properties similar to that 

 of rhubarb, but the astringent principles predominate. It is fusi- 

 form, about 100 mm. (4 in.) long and 20 mm. ( in.) thick, with a 

 thick orange-red cork, partially removed; a cross-section shows a 



