Oxygonum

Annual or perennial herbs, rarely shrubs. Ochreae present. Flowers polygamous and heterostylous, borne in axillary elongated racemes. Male flowers with a very short tube and 4-5 petaloid perianth segments. Bisexual flowers tubular; perianth segments persistent, the tube accrescent in fruit. Pedicels of bisexual flowers lengthening and thickening, those of the male flowers withering. Stamens 8, in 2 series, 5 outer and 3 inner. Styles 3. Fruiting perianth unarmed or with 3 prickles, sometimes winged.