 Growing to tall by wide, it is an erect perennial, with 3- to 5-lobed ovate, leathery leaves.Dense panicles of blue flowers are produced in late summer and autumn.It is valued as a garden plant, and numerous cultivars have been developed, of which 'Arendsii' and 'Kelmscott' (Wilsonii Group) have gained the Royal Horticultural Society's Award of Garden Merit.