Bowles Mauve РErysimum linifolium 

Bowles Mauve, Erysimum linifolium, is a type of wallflower. It is one of the best garden flowers for butterflies and also attracts honey bees, bumble bees, other bees, and hover flies. It is a small shrub that lives for about 2 years and can be propagated via cuttings. It is unable to set seed, so has an exceptionally long bloom period from April to November.