MEMOIRS FROM THE DEPARTMENT OP BOTANY OF COLUMBIA COLLEGE. 7 



properties. From that early time to the present, it, Kke many plants, has been used in 

 the practice of medicine. The genus is of economic interest from three points of view : 



First: Some of its members possess medicinal properties to a greater or less extent.-^ 

 The rootstock of P. Bistorta and doubtless that of its analogue, P. bistortoides, contains 

 much tannin and yields gallic acid. It acts as a powerful astringent. In Europe the roots 

 of P. amphibiuvi are often substituted for the true sarsaparilla and in many cases preferred 

 to it. On the other hand, P. Persicaria, a species possessing no peculiarly active prin- 

 ciples, was during the Middle Ages thought to have the extraordinary power of changing 

 the seat of disease from one part of the body to another. P. Hydropiper, whose foliage is 

 remarkably acrid in the fresh state, is a powerful diuretic and acts as a strong vesicant. 

 Other species are also very acrid, as our P. punctatum, which has been said to yield a 

 doubtful substance called polygonic acid, which forms in small green deliquescent crystals. 

 Astringent and, diuretic properties exist in P. Virginianum, but the most interesting plant 

 seems to be the common P. aviculare, whose fibrous roots are said to be used as a substi- 

 tute for quinine in northern and middle Africa, and whose seeds are, according to Lind- 

 ley, emetic and cathartic. This latter property is so remarkable in the genus that De 

 CandoUe thinks the power must lie in the testa and not in the albumen of the seed. 



Second : The genus serves as a food plant in some countries. Buckwheat flour, de- 

 rived from the seeds of Fagopyrum Fagopyrum, which has by some authors been included 

 in the genus Polygonum, is widely used. The fruit of P. scandens, P. Convolvulus, P. 

 cilinode and others may be substituted for it, although they contain much less nutritive 

 matter. In China the achenes of Fagopyrum emarginatum are eaten to a great extent, 

 and the roots of P. multiflorum are used in the raw state but become bitter and unpala- 

 table when cooked. On the other hand, in Siberia a fecula is made from the large root- 

 stocks of P. Bistorta, and this roasted forms an important food supply in certain districts. 



The third point of economic interest regards the dyeing properties of the genus. P. 

 Hydropiper imparts a yellow color to wool, and has]been used for many years in different 

 parts of Europe. I was informed by the late Mr. Thomas Hogg that in China and Japan 

 a purple dye is made from P. tinctorium. This color resembles indigo and is extensively 

 employed. The whole plant of P. amphibium is said to be used for tanning in the 

 Western States, and a given quantity will make one-third more leather than a like quan- 

 tity of oak bark, this species containing eighteen per cent, of tannin opposed to twelve 

 per cent, of the amount present in the best oak bark.^ 



iLindley, Fl. Med. 360-363. 2 Coulter, Bot. Bull. 1 : 30. 



