Paul Harcourt Davies / Bistort flowers (Persicaria bistortum), Piano Grande, Sibillini, Umbria, Italy. June 2016

Paul Harcourt Davies / Bistort (Persicaria bistortum) flower with hoverfly, Piano Grande, Sibillini, Umbria. June.

Nick Upton / Meadow bistort (Bistorta officinalis / Polygomum bistorta) flowering in profusion on Piva plateau, near Trsa, Montenegro, July.

Robert Thompson / Bistort (Polygonum bistorta) near Lac du Bornon, Mercantour National Park, Provence, France, June.

Radomir Jakubowski / European bistort (Bistorta officinalis) flower, Vosges Mountains, France, June.

Konrad Wothe / Mass of Polygonum flowers ( Polygonum bistorta) low angle view, Upper Bavaria, Germany. May

Christophe Courteau / Bistort {Polygonum bistorta} flowers, Botanic gardens, Berlin, Germany

Florian Möllers / Wetlands meadow with Common bistort (Polygonum bistorta) in a nature reserve in Berlin, Germany.

Andy Sands / Red Clover (Trifolium pratense) and Common Bistort (Persicaria / Polygonum bistorta) growing with Buttercups in hay meadow, Upper Teesdale, Co. Durham, UK, June

Michel Poinsignon / Cotton grass {Eriophorum linaigrette} and Bistort {Polygonum bistorta} flowers, Lorraine, France

Silvia Reiche / Ocellate Bog Fritillary (Boloria eunomia) on Common Bistort (Polygonum bistorta) flower, Germany

Silvia Reiche / Ocellate Bog Fritillary (Boloria eunomia) on Common Bistort (Polygonum bistorta) flower, Germany