Sometimes known as Joe Pye weed, this is a tall herbaceous perennial from the Asteraceae (Daisy) family, which hails from the North American prairies and does well in Sydney gardens. It grows quickly over the warmer months to a height of between 1.5 and 2m, and in late summer produces giant heads of fluffy pinkish-purple flowers, providing a statuesque background. It combines well with ornamental grasses to give a classic 'prairie' look, but looks equally effective with tall subtropical flowers such as Salvia, Dahlia, Brillantaisia and Canna in colours of pink, white, blue and cerise.
It likes to be planted in full sun, with reasonable soil and adequate moisture. It needs to be cut to the ground in winter. Despite its height, it rarely seems to need staking. Propagation is by division in early spring.There are several cultivars, including 'Gateway' and 'Purple Bush'. The correct naming of the plant is rather unclear; some authorities refer to it and its cultivars as belonging to Eupatorium maculatum (Atropurpureum Group).
Postscript: I eventually removed this plant - I loved the flowers but the blooming season was too short for me and they were taking up too much space in my garden.