The botanists have had a fine time with these plants, which have also been known as Polygonum, but they seem to have settled as Persicaria – until someone has another go at them. There are some tall species, some of which are invasive, but the low alpine kinds make excellent ground cover, without ever getting out of control. They spread outwards, rooting as they go, but the green mass is punctuated all summer by the seemingly endless succession of flowering spikes, which change colour as they mature.

Persicaria (Bistorta) affinis 'Superba' is an excellent ground-cover plant, with spikes of flowers that change from white to pink to quite a dark red, so that all colours are present on different stems at the same time - a display that lasts for many weeks.