Polygonum  

Herbs, stems with swollen nodes. Leaves simple, spiral. Ocreae lacerate. Inflorescence fasicled, determinate, bisexual. Flowers fasicled, tepal united at base, 5-merous, in two series, persisted in fruit, glandular nectaries present. Stamens 5, filaments base adnate with tepal, anthers dorsifixed. Ovary with 3 clefted styles. Fruits triangular.