the plant family Polygonaceae, characterized by herbaceous plants, vines, shrubs, and trees having stems with swollen joints, simple leaves, small, petalless flowers, and fruit in the form of an achene, and including the buckwheat, dock, knotweed, rhubarb, sea grape, and smartweed.
a smartweed, Polygonum persicaria, of the buckwheat family, having pink or purplish flowers and lance-shaped leaves with a spot resembling a thumbprint.
