WATER-HEMP, AGROMONY, a genus of the polygamia squamosis order, belonging to the syngenesia class of plants. Of this genus Linnaeus enumerates 13 species; but none of them appear to merit notice except the tripatria, frequently found by the sides of rivulets, ditches, and lakes, both in Scotland and England. This grows to the height of two feet; and hath its leaves divided into three, or often five, lanceolate serrated lobes, with yellow flowers, which are succeeded by flatish angular seeds, having two beards arising from the angles, which are hooked or barbed downwards; and generally they have another shorter beard arising from the middle of the back of the seed.

"As this plant (says Mr Lightfoot+) is found by a chemical analysis to possess much the same qualities as the celebrated verbena acmea, a plant belonging to a genus very nearly related to this, it is probable it would have the same good effects in expelling the stone and gravel. A decoction of this plant with alum dyes yarn of a yellow colour. The yarn must be first steeped in alum water, then dried and steeped in a decoction of the plant, and afterwards boiled in the decoction. The seeds have been known sometimes to destroy the cyprinus auratus, or gold fish, by adhering to their gills and jaws."