Your plant looks like a Salvia haematodes form or S. transsylvanica. S. pratensis is similar and S. haematodes is often considered to be a form of pratensis, and of unknown, probably garden, origin. May Night is a nemerosa form, of hybrid origin, with pratensis as a parent. A serious DNA study will be needed to help untangle this group of sages.

Thanks Rich. Interesting! My plant seems to have smaller, paler flowers than either of those, with longer internodes between the flower clusters on the flower spike. Almost like a Phlomis. I have a suspicion it's not a specific species but is a seedling out of who knows what. If the seller collected seeds out of May Night, this could be a revertant or some such. Oh well. I like knowing the real names for things in my garden, but sometimes that's just not possible! Thanks for you help!