A SMALL green herb, consisting of single, little roundish leaves, which float upon the surface of the water, and send their roots into it for nourishment, without sticking them into the mud. It is the small green herb that covers almost all our standing waters in summer. There are two other kinds of it, one with smaller leaves and many fibres from each, another with only one fibre from each leaf: both these are green all over; and a third kind with larger leaves, which are purple underneath, but all these have the same virtue, and it is no matter which is taken. The juice is to be given; and it is to be continued for several days.
It works powerfully by urine, and opens obstructions of the liver: jaundices have been cured by it singly.