Some of the Persicaria have been renamed to Bistorta. I don't know which ones, but I'm guessing this is one. These leaves look different from the ones I just posted from UBCBG at September 2021 in the Garden - plenty of flowers to see. Here is a Botany Photo of the Day for Bistorta affinis ‘Border Jewel’ | Botany Photo of the Day (ubc.ca).
Hi Wendy, I think I figured out which one it is after some reading. I believe it is P. longiseta (see picture below from today). It seems it is still in the genus Persicaria.
Good job! It does look like that, with appropriate invasive behaviour too. I like the common name: Oriental lady's thumb smartweed! Persicaria longiseta (Oriental lady's-thumb smartweed): Go Botany (nativeplanttrust.org) has a good description. Thanks for posting your additional photo of the sheathing stipule.
