POLYGONACEA. 653 
racter is principally due to the presence of salts of oxalic acid. 
The fruits and roots of several species are more or less nutritious. 
Coccoloba uvifera, Seaside Grape.—From the leaves, wood, and bark 
of this species a very astringent extract is obtained, which is commonly 
known as Jamaica Kino. The fruit is acid and edible, but not much 
esteemed. 
Fagopyrum.—tThe fruits of F'. esculentum (Polygonum Fagopyrum), Com- 
mon Buckwheat or Saracen Corn, of F. tataricym, and other species, are used 
as a substitute for corn in the northern parts of Asia and Eastern Europe, 
and also in Brittany and other parts of the world. The former species is 
cultivated in Britain as food for pheasants. This plant when in flower pro- 
duces an effect on many animals resembling intoxication, and a case has 
been reported within the last few years in which many lambs were in this 
way stupefied and ultimately killed by it. 
Polygonum.—The rhizome of P. Bistorta, commonly called Bistort root, 
is a powerful astringent, which property is due essentially to the pre- 
sence of tannic acid. Starch is also one of its constituents, hence it pos- 
sesses, to some extent, nutritive properties, and is sometimes eaten, when 
roasted, in Siberia. The young shoots and leaves have been used from an 
early period in the North of England as a pot-herb under the name of Pas- 
sions, probably from the plant being in perfection for such a purpose about 
Eastertide. The roots of P. viviparum are also used as food by the Esqui- 
maux. The leaves of P. Hydropiper are very acrid, hence the common name 
of Water-pepper which is given to this plant. This species also yields a 
yellow dye. From P. tinctorium a blue dye resembling indigo is obtained 
in France, &c. The Chinese produce a blue dye from several species of 
Polygonum. 
Rheum, Rhubarb.—The species of this genus usually possess more or 
less purgative and astringent properties; this is especially the case with 
their roots, and hence these are largely used in medicine. Various species 
of Rhubarb are indigenous or cultivated in different parts of the world, but 
until recently the botanical source of our official rhubarb root was unknown, 
and cannot even now be said to have been absolutely determined. It seems, 
however, almost certain that whilst the plant described by Baillon under 
the name of Rheum officinale may vield some of it, that the source of the 
best official rhubarb—namely, that which formerly came to us by way of 
Kiachta, and commonly known as Russian Rhubarb—is derived from R, pal- 
matum, a plant which is a native of Tangut, in Kansu, the extreme north- 
western province of China. In this province rhubarb is principally obtained 
from wild plants, but also to some extent from cultivated ones. Rhubarb from 
this species is also derived from the Chinese provinces of Szechuen and Shensi. 
The rhubarb thus obtained from R. palmatum is chiefly exported by way of 
Shanghai, but also to a small extent from other ports, as Tientsin, Canton, 
Amoy, and Foochow. In the British Pharmacopceia the root is said to be 
derived from R. palmatum, R. officinale, and probably other species. The 
kind known as Indian or Himalayan Rhubarb is the produce of several 
species, but more especially of R. Moorcroftianum, R. australe, and R. 
Emod', English Rhubarb is chiefly derived from R. Rhaponticum, and is 
now much used in the hospitals of this country, and in America, but it is 
not so active as the official rhubarb, although probably equally efficacious 
when given in sufficient doses. Some English rhubarb is also obtained from 
R. officinale, which is now also cultivated in this country. The petioles of 
R. Ribes are employed in the East for the preparation of sherbet. The 
petioles of R, Rhapenticum and other species are used for tartsand puddings. 
Their acidulous character is principally due to the presence of oxalic acid. 
The roots of the species of Rheum contain abundance of calcium oxalate 
crystals (conglomerate raphides). (See page 34.) 
