Lysimachia atropurpurea

Thank you. Also known as Gooseneck Loosestrife, which I learned by googling. Very helpful.

No, Gooseneck Loosestrife is a different species and a running plant. Lysimachia clethroides is the gooseneck type, not very desirable in a garden setting as it invades.

Lysimachia atropurpurea is a lovely plant and not at all invasive. It is not the thug that lysimachia clethroides is. I used it for a terrace bed one year and it was knock down, drag out gorgeous. Supposedly perennial, I found it did not return the next year. However, I grew it from seed, so wasn't out much but the effort. Hard to get the seed for, and at one time was touted as a new offering in the trade, but didn't catch on. I suppose it's perseverance or lack of it didn't help.