Lesser Celandine

Years ago I bought and planted a perennial labelled Marsh marigold. It has since taken over my perennial beds and the wooded publicly-owned land behind my yard. I believe it is not marsh marigold (caltha palustris) at all, but rather lesser celandine (ranunculus ficaria) because it roots are definitely tuberous. I don't know what to do. Pulling is impossible - it is way beyond that stage and besides little tubers break off and just propagate more. I'm afraid to spray because they are intermingled with other perennials. Any suggestions?

Sounds like you've got a real problem there. I think this plant is pretty but to answer your question, if I were you I would try to pull them up around the other perennials and then I'd spray everything that is by itself.

If it were me and this issue happened, I might pull some around my other perennials but leave the wooded public lot alone and just enjoy the flowers.

I have used a big piece of cardboard made into a tube or 3 sided baffle, put it on the weed, then sprayed Roundup on the weed. If you leave the cardboard in place for about 10 seconds after you spray, the mist settles on the leaves and there is no damage to the perennial next to it. The intermingled weed roots get killed. Roundup is absorbed through the leaves not roots. You won't be able to do this in the public land, but can patrol your property line occasionally and hand weed. I try to avoid Roundup and other poisons, but hand weeding in this situation is very difficult.
I have a tall piece of cardboard and a tank sprayer with a wand, so this can be done standing up, but you could use a hand sprayer and short piece, and crawl around in the garden.

That's a great idea to keep transfer spray of good plants!

Thank you all for your suggestions. This spring I got out very early, before the other perennials were up and sprayed. I wound up losing quite a few perennials. :( As Pistil wrote the intermingled roots do get killed. Next spring, I intend to try to get out as early as possible and pull out what I can. I realize the tuberous roots will be left behind, but maybe if I do it repeatedly maybe the plants will "die of starvation" because they will not have any leaves exposed to light. I know its a slim chance, but I can't think of anything else. Oh and yes, sequoiadendron4, I will absolutely leave the woods alone.

I feel your pain, our lawn and beds are full of it. I've spent hours each spring hand-weeding the lawn as they are supposed to be toxic to rabbits, but obviously can't spray the lawn with weed killer as the bunnies eat it! It's been 9 years and I'm nearly there...

If you can get a hand fork to loosen soil around it, then pinch out the whole root
clump with your fingers, then you will get a lot of them out, especially if wait until it's rained so they come out easier. They will def leave some tubers behind but it gets less each time round. Good luck! 🙂

Thank you Shiny Sun. It's encouraging to know that, while it took you 9 years, they do eventually lessen.

Shiny Sun - did you do this work at any particular time? earliest spring or continually until they go dormant?