Bistorta vacciniifolia (syn. Persicaria)

Rock Knotweed. A choice mounding groundcover we got at one of the best alpine plant nurseries on the planet, Aberconwy Nursery in Wales. Dense trailing and mounding red stems lavishly adorned with Aug-Sept spires of pink flowers and glossily petite deciduous leaves. Lovely spiller in containers. Probably hardier than the zone 7b we know to be true.