Centranthus ruber . Grows prolifically out of dry limestone walls and cliffs in some areas and can become invasive, so should not be grown near sensitive dry wildlife areas. It doesn't like a competitive garden border situation. As well as butterflies during the day, lots of moths love it at dusk - especially the Silver Y moth and the Hummingbird Hawkmoth that are both summer migrants from the warmer continent. Hardy Perennial.
for the white flowered form see 'rare plants' section; for Valeriana officinalis, the herbal plant, see Wildfoods 'Herbs' section.
