POLYGONACE^. 565 



<dpinvs, under the name of Monk's-rliubarb, were formerly employed, 

 as purgatives. One of the most important plants of the order is the 

 Ehubarb-plant. The officinal Rhubarb is the root of Rhewm oficinale 

 of Baillon. It was discovered in south-eastern Thibet, and it is also 

 said to grow in various parts of western and north-western China, 

 whence the supplies of Rhubarb are derived. The extent of country 

 from which Rhubarb of one kind or another is actually collected, 

 according to Christison, stretches from Ludak, in 77|° east longitude, 

 to the Chinese province of Shen-si, 29° farther east, and from the 

 Sue-chan mountains, in north latitude 26°, nearly to the frontiers of 

 Siberia, 24° northward. The best Rhubarb is said to come from the 

 very heart of Thibet, within 95° east longitude and 35° north lati- 

 tude, five or six hundred miles north of Assam. The following are 

 the species of Bheum said to yield Rhubarb : — 



1. Rheum officinale, Baillon, the true officinal rhubarb-plant. 



2. Mhewn palmatwm, h. At one time considered the rhubarb-plant. 



3. Rheum undulatum, L. , which yields much of the French rhubarb. 



4. Bheum compactum, L. Another species yielding French rhubarb, and 



often cultivated in Britain for its acid petioles. 



5. Rheum JSmodi, Wall. This species yields a kind of Himalayan rhubarb. 



Its petioles are used for their acid properties. 



6. Rheum rhapontieum, L. Used in France and Britain in the same way as 



the fourth species. 



7. Rheum hybridum, Murr. Much cultivated in Germany for its root, and 



in Britain for its stalks. 



8. Rheum Webbianum, Royle. A Himalayan species. 



9. Rheum spiciforme, Eoyle. Another Himalayan species. 



10. Rheum Moorcroftianum, Boyle. Another Himalayan species. 



11. Rheum crassinervium, Fisoh. A Russian species. 



12. Rheum leucorhizum, PaU. A Siberian and Altai species, said to yield 



imperial or white rhubarb. 



13. Rheum Oaspicum, Fisch. A Caspian and Altai species. 



14. Rheum Ribes, L. An Afghanistan and Persian species. 



All these species grow in the cold parts of the world, as on the Altai 

 mountains, in Siberia, Thibet, North of China, a,nd on the Himalayan 

 range. The rhubarb procured from one or more of these species is 

 known in commerce under the names of Russian or Turkey, Chinese 

 ■or East Indian, and English rhubarb. Rhubarb contains raphides of 

 oxalate of lime (p. 11), along with tannin, gallic acid, resin, and a 

 peculiar yellow-coloured principle called rhabarberin, which seems to 

 be identical with chrysophanic acid. Raphides form from 35 to 40 

 per cent of Turkey rhubarb, and give rise to its grittiness. These 

 crystals are less abundant in the other varieties of rhubarb. Rhubarb 

 is employed medicinally as a cathartic, astringent, and tonic, in the 

 form of powder, pill, extract, tincture, wine, and infusion. The stalks 

 of Bheum nobile are eaten in Sikkim. Coccoloba mifera, Seaside-grape, 

 so called from the appearance of its fruit, yields an astringent sub- 

 stance called Jamaica Kino. 



