Water-Pepper, Lakeweed, or Biting Snakeweed, Polygonum hydropiper, L. an indigenous plant, growing on the sides of rivulets, lakes, and ditches ; flowering from July to September. - The whole of this vegetable possesses a very acrid taste : its fresh res have, nevertheless, with advantage been applied externally, Tor cleansing old fistulous ulcers, and consuming fungous flesh. An infusion of these leaves is said to promote the urinary discharge in phlegmatic habits; and has frequently been of service in scorbutic complaints. When mixed with soft soap, the ashes of the lake-weed are used, as a nostrum, for dissolving the stone in the bladder. - According to Dr. Withering, the acrimony of this herb rises on distillation ; and 2 or 3 half pints of the water, drunk daily, have been found very effectual in some nephritic cases. It imparts a yellow colour to wool. The Water-Pepper is refused by every spe-cies of cattle. - See also Blister.