Pol-i-go-na'se-e. L. Poliqon-um + aceae, fr. Gr.
knee, joint - i. e., from stem s numerous joints. Herbs, shrubs. Distinguished by acrid, astringent, purgative properties, stems composed of many swollen joints, with ocreate stipules above each; flowers perfect, on jointed pedicels; calyx 3-6, greenish or petaloid, inferior; ovary 1-celled, superior, styles and stigmas 2-3; stamens 6-9; fruit 3-angled, seed solitary; temperate climates; astringent, purgative; contain oxalic acid and oxalates. Genus: 1. Rheum.