ilONOCHLAMTDE^. 621 



gitudinally. Ovary superior {fig. 1001), 1-celled ; styles and 

 stigmas 2—3 (figs. 1001 and 1002) ; oy?(/e solitary (figs. 710 and 

 719), orthotropous. Fruit usually a triangular nut (fig. 1002). 

 Seed solitary, erect ; embryo (fig. 758) usually with farinaceous 

 albumen, inverted, with a superior radicle. 



Distribution, ^c. — Generally diffused over the globe, and 

 particularly so in temperate regions. Examples : — Eriogonum, 

 Oxyria, Rheum, Polygonum, Coccoloba, Rumex, Triplaris, 

 Brunnichia. There are about 34 genera, and 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 oxahc acid. The 

 fruits and roots of several are more or less nutritious. 



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 they are largely used as medicinal agents. Various species of 

 Rhubarb are indigenous or cultivated in diflFerent parts of the world, but the 

 exact source of our officinal rhubarbs is at present unknown. Royle says, that 

 " the Rhubarb country (from which they 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 

 are Russian or Turkey, Chinese or East Indian, Himalayan, and English. 

 The Russian is the best, but its botanical source, as noticed above, as also that 

 called Chinese, is unknown. Himalayan Rhubarb is the produce of several 

 species, more especially of R. Moorcrqftianum, Webbianum, and Emodi. En- 

 glish rhubarb is obtained from R. Rhaponticum, and is now extensively em- 

 ployed 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 used in the East 

 in the preparation of sherbet. The petioles of R. Rhaponticum and other 

 species are used for tarts and puddings. Their acidulous character is princi- 

 pally 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. 25.) 



Polygonum. — The root of P. Bistorta, commonly called bistort root, is a 

 powerful astringent, which property is due to the presence of tannic acid. 

 Starch is also one of its constituents, hence it possesses nutritive properties, 

 and is eaten when roasted in Siheria. The roots of P.viviparum, are also 

 used as food by the Esquimaux. The 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. 



Fagopyrum. — The fruits of F. esculentum. Common Buckwheat, of i^. tata- 

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

 of Asia and Eastern Europe. The former species is cultivated in Britain as 

 a food for pheasants. 



Coccoloba uvifcra. 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. 



Rumex Several species possess acid properties owing to the presence of 



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

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

 acetosa is sometimes used medicinally for its refrigerant, diuretic, and antiscor- 

 butic properties. In times of scarcity, it has been employed in Scandinavia as a 

 substitute for bread. The root of R. Hydrolapathum, Great Water Dock, is 

 astringent and antiscorbutic. The roots of R. alpinus are purgative, and 

 were formerly employed instead of Rhubarb under the name of Monk's 

 Rhubarb. 



Natural Order 181. NTCXAGiNACEiE. — The Marvel of Peru 



