This is veronicastrum virginicum, otherwise know as Culver’s Root (a name I’m not sure is much better). In my yard, it might as well just be known as “bumble bee bush” or some such thing.
I really didn’t even want to disturb the work of the bees but every spike of flowers–and these spikes begin blooming in late June and go on for at least a month or more!–had 3 or 4 bumble bees of different sizes plus smaller bees.
This one even had one of these glorious golden digger wasps! (look on the lower right of the spike in the foreground). I didn’t know they came in for pollen. I watched it for quite some time. Rather than buzzing from flower spike to flower spike, it just walked. Fascinating!
A word of caution about this plant–it towers about six feet in my garden so it’s not for the well-behaved gardener. In fact, this is in what I used to call my “wildlife garden.” Things have grown so well that I now just refer to it as the “Wild” garden (although the pollinators love it!)