Polemonium pauciflorum

This is an unusual Polemonium, Kniphofia, with the yellow colouration. I had it from seed years ago but I had the impression it was not very perennial?? Have you had it long enough to find out, if not, take some seeds.

I had this plant years ago in my garden in Yorkshire. I gave some to my sister who's had it ever since, it seeds around quite well she says, and it has appeared in several pots of plants she's given me this year.