Caryopteris x clandonensis or the Blue-Mist Shrub is an attractive deciduous shrub that grows into a dense rounded bun-shape and works well in borders and shrubberies.
The leaves are grey green and have serrated margins while the flowers are a brilliant purple/blue and are borne on flattened spikes in summer.
The cultivar 'Summer Sorbet' has yellow edges to the leaves and is very attractive even when not in flower.