546 MEDICAL BOTANY. 



tainous parts of Europe. The root is large, fleshy, and purgative like 

 Rhubarb. Although at one time in much use, especially among the inmates 

 of monasteries, whence its name of " Monk's Rhubarb," it is now seldom or 

 never employed ; and Merat and De Lens are of opinion that its powers are 

 very feeble ; Linnseus, however, took it for a variety of Rheum rhaponticum. 

 Several of the plants of this genus have acid leaves, owing to the presence 

 of oxalic acid ; among these are R. acetosa, R. acetosella, and R. vesicarius. 

 The first of these is much used as a culinary vegetable in France, and is 

 esteemed very wholesome. Its employment for this purpose is of very ancient 

 date, as Pliny speaks of it as rendering animal food easier of digestion. They 

 are all cooling and aperient, and somewhat diuretic ; but are prejudicial 

 when too freely or frequently eaten, from the quantity of oxalic acid they 

 contain. This is extracted in Switzerland, and forms part of the oxalic 

 acid of commerce ; it is said that it requires fifty pounds of leaves to produce 

 two and a half ounces of pure acid. A decoction of the leaves is much em- 

 ployed in France as a depurative remedy, especially in the spring. 



Polygonum. — Linn. 



Calyx turbinate, coloured, with five deep, ovate, obtuse, persistent segments. Stamens 

 5 — 8, very short, subulate. Anthers roundish, incumbent. Ovary roundish, somewhat 

 triangular or compressed. Styles usually three ; in those with a compressed ovary, two, 

 filiform, short. Stigmas simple. Nut solitary, either triangular or compressed, pointed. 

 Embryo enveloped in a farinacous albumen. 



Almost all are herbaceous, with alternate leaves, sheathing at the base, and 

 varying much in shape in the different species; furnished with ochrese. 

 Flowers axillary or terminal, usually spiked. Peduncles articulated. Stems 

 and branches often nodose, but not articulated. The species are polymor- 

 phous, and require revision. They are principally natives of Europe and 

 North America ; some few are found in the eastern parts of Asia. They 

 differ as widely in their medical properties as they do in their botanical cha- 

 racters, some being astringent, others very acrid, whilst others afford farina- 

 ceous and edible seeds. The most important species of the first class is P. 

 bistorta, a native of the north of Europe and America. It usually grows in 

 damp situations, and has a creeping, fleshy, or woody root, which is power- 

 fully astringent; this has been employed with benefit in all cases requiring 

 the use of this description of remedies, and has also been recommended in 

 combination with one of the pure bitters in intermittents. It contains much 

 tannin and gallic acid ; it also abounds in fecula, and is used in Siberia for 

 food, after being roasted. The fibrous root of P. aviculare is also said to be 

 astringent, and was at one time much esteemed as a vulnerary. The seeds 

 are emeto-cathartic ; this property, so unusual in the genus, is thought by 

 De Candolle to reside in the testa. R. tamnifolium is employed in some 

 parts of South America as art astringent in hemorrhages. 



The acrid species are very numerous ; but those which have been most 

 generally employed are P. hydropiper and P. persicaria. The leaves of 

 both these are very acrid and pungent, and will even vesicate when applied 

 in a fresh state to the skin. Like most acrid plants, they become inert by 

 desiccation. Many marvellous qualities have been attributed to the last of 

 these species by the writers of the middle ages ; that it was capable of chang- 

 ing the seat of disease from one part of the body to another, &c. At a much 

 more recent period, some of the most eminent writers in the profession 





