From Persica, the peach, referring to the similarity in leaf shape of these two genera.
Annual or perennial erect or sprawling herbs, occasionally with rhizomes. Leaves not jointed, stalkless or with a short stalk. Sheath tubular, usually with long hairs at the tip. Flowers mostly bisexual, terminal or axillary in heads or, more often branched clusters. Perianth segments 4-5, petal-like. Stamens 4-8. Nut surrounded by persistent perianth. [formerly Polygonum in part]
P. hydropiper (L.) Spach, Water Pepper, is a widespread weed of wet places in Australia and the northern hemisphere.
Plants occasionally cause dermatitis to stock and humans.
Division or cuttings.
Perianth segments mostly 5, not winged or ridged; leaf stalks without nectaries.
About 150 species, cosmopolitan (Australia 15 species, all states).
Source: (1997). Polygonaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.