I first learned about this plant several years ago when I was visiting the dentist. In front of his office was a gorgeous bush covered in blue flowers. I stopped to look and noticed it was infested with honey bees . . . hundreds of them.
I simply had to have one of these, so on the way home I stopped at a nursery. They had lots and lots of what appeared to be the same variety, also covered in honey bees. When I asked the sales person if the bees came with the bushes, she got amazingly flustered. I felt bad for her . . . and kind of embarrassed.
Anyway, I learned the bush was a species of Ceanothus, more commonly called California lilac. The plants belong to the Buckthorn family (Rhamnaceae) and are highly prized as garden shrubs.
The genus Ceanothus includes roughly 55 species, almost all of which are native to western North America. Most are evergreen shrubs or small trees. The garden varieties come with blue, white, or pink flowers and are amazing drought tolerant once established. The flowers are visited by butterflies, wild bees, and other pollinators and the seeds are consumed by birds and small mammals.
Oddly, the bush I have never attracts honey bees but is routinely visited by all types of bumble bees, hover flies, and butterflies. The furry little bumble shown below visited just last week.