This hardy, zone 2 perennial modestly attracts hummingbirds on its flower filled stalks. Each tiny flower provides enough of a tease to keep them returning. "Veronica" is also available with darker pink flowers. I have found the blue colour to be more hardy and it even self seeds occasionally. It's not been invasive in my zone 2 and 3, but I'm not sure how invasive it'll be in much warmer climates. Either way it produces several branches of flowers for about 6-8 weeks, depending on the maturity of the plant.
Any time a hummingbird spends enough time feeding from a flower for me to get a few photos, it gets placed on the keep list of annuals or perennials. For those of you that live in a colder climate like myself, and have trouble finding a perennials that winter over, this one is a keeper. 2015. Juvenile Ruby-throated hummingbird. N.E. of Edmonton, Alberta.