any of a genus (Polygonum) of annual or perennial plants of the buckwheat family, having conspicuous enlarged nodes, ocreae, and small whitish, greenish, or pink flowers in the leaf axils or in terminal clusters
See polygonum in American Heritage Dictionary 4
(pə-lĭgˈə-nəm)
noun
Any of numerous plants of the widely distributed genus Polygonum, characterized by stems with knotlike joints and conspicuous sheathlike stipules.