POLYGONACE^E. 



%* This genus is very important, on account of the officinal rhubarb 

 being produced by some of the species. It is, however, not a little 

 curious that up to the present time no one should have ascertained with 

 certainty from which of the many known species any of that which finds 

 its way to Europe through Turkey and Russia, is really obtained. 



The species inhabit the plains of Tartary, the wastes of Siberia, and 

 the lofty mountains cutting off India from the high and cold table land 

 to the north. They are all similar in their flowers, but their leaves, 

 particularly the leafstalks, afford excellent marks of distinction when 

 the plants are wild. In the gardens they hybridise so readily, that it 

 hardly possible to say to which of the wild types the many culti- 

 vated sorts are referable. In the following account, I have included 

 every species with which I am acquainted, or of which an account can 

 be found in books. There is some confusion in the synonymy, which 

 I have endeavoured to adjust ; but the genus requires all the care of a 

 skilful monographist. Guibourt seems to me to have studied the 

 subject with more attention than any one ; and I have accordingly 

 incorporated his opinions in the following short history of the spe- 

 cies. 



It will be seen that the whole subject is involved in the greatest 

 obscurity : and it is probable that Professor Royle is correct in his 

 opinion that the officinal drug, obtained in the heart of Thibet, whither 

 no botanist has ever penetrated, is the produce of some species still 

 unknown. I extract the following account of the origin of officinal 

 rhubarb from this gentleman's excellent Illustrations of the Botany of 

 the Himalaya Mountains, $c. " The rhubarb of commerce is well known 

 to be brought by the Chinese to the Russian frontier town of Kiachta, 

 according to the treaty formed between those powers in 1772. The 

 Chinese obtain the rhubarb produced in China Proper, from that part 

 of the province of Shensee now called Kansu, situated between N. 

 lat. 35 and 40 ; but the best, according to the missionaries, who say it 

 is called Tai-hoang, in the province of Letchuen, from the moun- 

 tains called Sue-chan, or of snow, which extend from N. lat. 26 to 33 

 and from about 100 to 105 of E. longitude. That from the latter 

 province probably forms much of what is called China rhubarb : the 

 missionaries met large quantities of it, brought down in the months of 

 October and November. That from Kansu may afford some of what 

 is called Russian rhubarb ; but both Pallas and Rehman have ascer- 

 tained that the greater portion, if not the whole of this, is obtained in 

 April and May from the clefts of rocks in high and arid mountains 

 surrounding lake Kokonor. Bell also learnt that it was the produce of 

 Mongolia, and Marco Polo of Succuir, in Tanguth. Dr. Rehman 

 ascertained that the trade is in the hands of one Bucharian family, who 

 farm the monopoly from the Chinese government, and reside at Si-ning, 

 a Chinese town on the very frontiers of Tibet, 3000 verstes from Kiachta, 

 and 20 days journey from Kian-sin and Schan-sin, Tangutian towns, 

 where the Bucharians go to purchase rhubarb. This would bring the 

 rhubarb country within 95 of E. long, in 35 of N. latitude, that is in 

 the heart of Thibet. 



732. R. Emodi Wallich MSS. Cat. herb. ind. No. 1727. 

 Hooker in Bot. mag. t. 3508. R.australe Donprodr.fl. nep. 75.; 



id. in Sweet Fl. Gard. t. 269 Mountains of Gossain Than, 



Kamaon. 



354 



