Spires of blooms are characteristic of the so-called 'obedient plant' Physostegia virginiana (ht to 1m), which is obedient only in the sense that its tubular flowers remain wherever they are pushed on the 60cm stems. Its tough fleshy roots like to spread through garden borders, so it must be controlled regularly by digging up and discarding the excess rosettes of leaves it forms. It is a tough clump-forming herbaceous perennial originally from the North American prairies. There are purple and white forms, with the white one often failing to do well in our Sydney gardens
These plants bloom in late summer and early autumn, and do best in full sun in any reasonable soil with good drainage. They will stand periods of dryness and heat quite well. If the main stems are cut below the flowering stalks once blooming is over, and the plant fertilised, a second crop of flowers may emerge. The stems can be cut to the ground in winter.
Postscript; Though I love the look of this plant, I ended up removing it because it just spread too much. I still enjoy seeing it in other people's gardens!