314 ILLUSTRATIONS OF THE BOTANY OF [ Polygonee. 
nana ascends to 5,892 feet on Mount Cenis. Species allied to these are found at 
considerable elevations in the Himalayas, as at Theog and Phagoo, and a species 
resembling P. maritimum, at Chango and Kanum in Kunawur, where the soil has been 
shown to be saline. The section Persicaria attains the next greatest height, as 
P. segetum is found at an elevation of 8,160 feet on the Andes, and P. Persicaria var. 
nana at 3,054 feet on the Alps; so in the Himalayas we have P. spherostachyum, Bru- 
nonis, vaccinifolium, Emodi, speciosum, and oryphyllum, on such mountains as Mussooree, 
Choor, Kedarkanta, and Peer Punjal, or from 7,000 to near 13,000 feet of elevation, 
and on the Kherang, Chandow, and other passes. -P. viviparum, Lin., is also found 
in such situations, with a new species, P. bulbiferum, nob., nearly allied to it. The 
section Tiniaria does not ascend so high, P.tamnifolium, existing from 5,400—7,200 
feet on the Alps; and in the Himalayas, P. pterocarpum at Mussooree, &c., and 
P. Convolvulus, Lin., at Leeo in Kunawur. The species of Fagopyrum, with the 
exception of F. triangulare, are found in a cultivated state. Rumer Nepalensis occurs 
everywhere; and R. hastatus, found at the foot of the mountains, is allied to R. Aceto- 
- sella. . fF ah 
Kenigia, found in Iceland and Lapland, occurs also in the higher mountains of 
Nepal; so Oxyria, indigenous in the mountains of Scotland, Siberia, North America, and 
Melville Island, has also a species, O. elatior, in the Himalayas, on such mountains as 
Peer Punjal, and in Kunawur. This Dr. Meisner describes as ‘‘ O. reniformi nimis 
fere affinis;” and though generally distinguished by its greater size, I have specimens 
varying from one inch to a foot and a half, so that the emargination of the winged seed 
remains as the only character, and this also varies in degree in different specimens. 
The genus Rheum, or RuvBars, so important in a commercial point af view, is more 
interesting than any other in its geographical distribution. R. Rhaponticum is found in 
several parts of Russia, on the shores of the Bosphorus and of the Caspian Sea, east- 
wards in Siberia, and the lower mountains of the Altai Range: &. sibericum and 
undulatum of Pallas are considered by Ledebour to be only varieties of this. &. /eucor- 
hizum (nanum Sievers) is also found in the Altai mountains and the deserts of the Kirghis. 
Neither of these afford the Rhubarb of commerce, which is not found within the Russian 
territories, but well known to be brought by the Chinese to the Russian frontier town 
of Kiakhta, according to the treaty formed between these 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 
Setchuen, from the mountains 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 ascertained that the greater portion, if not the whole of this, is obtained 
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