This beautiful plant is the Hylotelephium telephium 'Purple Emperor', also known as Sedum telephium 'Purple Emperor', from the Crassulaceae family which was seen at The Wynyard Hall Gardens. It is a hardy deciduous perennial with succulent foliage that creates interest through its unusual burgundy-black colour and texture. In late summer the umbrel blooms of star-shaped deep red/lighter pink flowers which contrast the deep coloured foliage and red stems.
It's a perfect plant for borders, containers and loved by insects when nectar is scarce in the later months. The Sedum genus is loved by butterflies as you can see here: Vanessa atalanta.
Height: 50cm Spread: 45cm Hardiness: 7
Requires full sun in a south facing aspect with well drained soil.