Deciduous shrub 6-8 feet high and 3-5 feet wide. Terminal clusters of dark purple flowers, 4-10 inches long, are produced throughout the summer. In cold winter climates, it will often die back to the ground.
A favorite among gardens for attracting butterflies. Selected by Ruys at the Moerheim Nursery in the Netherlands around 1959. Awarded the RHS Award of Garden Merit in 1993.