In article ,
says...

About fifteen months ago I bought some Canna lily seeds (Indian shot)
on Ebay. I only got around to planting them a few weeks ago (serious
life-changing events intervened). Rubbed the seeds on sandpaper to
erode a bit of the outer coating, then soaked them for 24 hours,
before planting them singly in a seed tray. Two came up fairly quickly
(I'm waiting in hope for the rest!), but they look nothing like what I
was expecting, nor what I can find for images of Canna seedlings on
the Internet. https://ibb.co/5Frs7FD Does anyone recognise it? (please
tell me it's not Japanese Knotweed, although it looks a bit like it!)

Just a mad guess, could it be lab-lab bean/dolichos?

Janet.