288 FLORA HISTORICA. 



The generic name of these plants is derived 

 from the Greek, UoT^vyovoi^, from xoXw, many, and 

 yovov, knee, and it was so called in allusion to 

 the numerous knots in the stalks. The British 

 species of this genus of plants was formerly 

 called Knot-grass on the same account. The 

 name of Persicaria, by which several of the spe- 

 cies are distinguished, is of modern origin, and 

 was given to these plants on account of the foliage 

 of the kind principally used in medicine being 

 similar to that of the Peach-tree, which is called 

 Pcrsica in the Latin language. The leaves of 

 the Oriental Persicaria, are, however, quite of a 

 different shape, being large, and of a broad 

 oval shape inclined to a point, whilst the Persi- 

 caria Urens, Polygonum Hydropiper, has leaves of 

 a narrow oblong shape like those of the Peach. 

 Medical writers distinguish this species by the 

 name of Hydropiper, water and pepper, from its 

 hot acrid taste, and because it grows in wet si- 

 tuations, and most abundantly in places that are 

 under water in the winter. M. Tournefort tells 

 us, that the Eastern Persicaria was cultivated in 

 Asia, principally on account of its medicinal pro- 

 perties, which are similar to those of the Hydro- 

 piper or Water-pepper, which was formerly held 

 in high reputation in this country on account of its 

 efficacy in medicine, but its pungency is so great 



