need to identify a plant
This plant appeared in our garden some 10 years ago, and it had regrown each, over the years, but never in the same place it has moved some 3 feet north in the 10 years. It does not set seed and dies back each winter. It is such a lovely plant, but its reached the path and unless it chages direction it will fail to regrow next year. the flower spikes, usually 3 are some 3 feet tall, the flowers are about 25mm wide and a lovely blue. Can anyone identify it?