MOXOCHLAMYDE^. 621 



free {fig. 1002), more or less persistent, imhricated. Stametis 

 {fig. 1002) hypogynoiis or perigynous ; anthers dehiscing lon- 

 gitudinally. Ovary superior {fig. 1002), 1-celled; styles and 

 stigmas 2 — 3 {figs. 1002 and 1003) ; ovule solit<iry {figs. 713 and 

 721), orthotropous. Fruit usiially a triangular nut {fig. 1003). 

 /Sf<?c? solitary, erect ; embryo {fig. 761) generally with farinaceous 

 albumen, inverted, with a superior radicle. 



Distribution, ^-c. — Generally diflPiised over the globe, and more 

 particularly so in temperate regions. Examples of the Genera : — 

 Eheum, Polygonum, Coccoloba, Rumex. There are about 500 

 species. 



Properties and Uses. — Chiefly remarkable for the presence of 

 acid, astringent, and purgative properties. The acidulous cha- 

 racter is principally due to the presence of oxalic acid. The 

 fruits and roots of several 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 pleasantly acid and edible. 



Faqopiirum. — The fruits of F. esculentum. Common Buckwheat, of F. tata- 

 ricnm, and other species are used as a substitute for corn in the northern 

 parts of Asia and Eastern Europe, and in some other parts of the world. 

 The former species is cultivated in Britain as a food for pheasants. 



Polygonum.— T\\e root or rhizome of P. Bistorta, commonly called bistort 

 root, is a powerful astringent, which property is due essentially to the 

 presence of tannic acid. Starch is also one of its constituents, hence it pos- 

 sesses nutritive properties, and is sometimes eaten when roasted in Siberia. 

 The roots of P. viviparum are also used as food by the Esquimaux. Tae 

 leaves of P. Hydropiper are very acrid, hence the common name of Water- 

 pepper which is given to this plant. A yellow dye may be obtained from this 

 species. From P. tinctorium a blue dye resembling indigo is obtained in France, 

 &c. The Chinese produce a blue dye from several species of Polygonum. 



Rh^um, 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 

 the exact source of our officinal rhubarbs is at present unknown. Roylo 

 says, that " the Rhubarb country (from which tbey are derived) is in the 

 heart of Thibet, within 95° of E. long, and 35° of N. lat., and as no 

 naturalist has visited this part, and as neither seeds nor plants have been 

 obtained thence, it is as yet unknown what species yields the Rhubarb." 

 The principal kinds of Rhubarb which have been described by pharmaco- 

 logists are Russian or Turkey, East Indian, Dutch-trimmed, Hima'ayan, and 

 English. The first three are alone officinal. The Russian was the best kind, 

 but at present the old Russian sort is not to be met with, Himalayan Rhu- 

 barb is the produce of several species, more especially of R. Moorcro/lianum, 

 R. Webbianum, and R. Emodi. Enghsh rhubarb is obtained from .ff. Rha- 

 poniicum, and is now extensively employed in the hospitals of this country, 

 and in America, but it is not so active as the officinal kinds of rhubarb. 

 The petioles of R. Ribes are employed in the East for the preparation 

 of shertet. The petioles of R. Rhapontkum and other species are used for 

 tarts and puddmgs. Their acidulous character is principally due to the 

 presence of oxalic and malic acids. The roots of the species of Rheum 

 contain abundance of oxalate of lime crystals (conglomerate raphides). 

 (See p. 32.) 



Rumex. — Several species possess acid properties owing to the presence of 

 oxalic acid, especially R. acetosa, common Sorrel, R. Acetosella, R. scutatus, 

 and R. Patientia. They have been employed as pot-herbs, and for salads. R. 



