Polygonum, from the Greek polys many and gonu joint or knee, referring to the stems which are conspicuously swollen. Usually herbs or shrubs, sometimes twining; leaves simple, alternate with membraneous stipules which form a sheath or ochrea/ocrea around the stem. Flowers small, perianth 1-2 whorls, stamens usually 6. Ovary unilocular with 2-4 styles; fruit usually an angular nut enclosed in the persistent perianth.