Name the weed

[Zingzingerella]

Anyone know what these triffids are that have invaded and how to get rid of them permanently?
They've spiky ridge running the underside of leaves and their bases collect stinky ponds of water.

I made do with chopping most of them at the base the stalk but assume will regrow. I've inherited more of a weed patch than a garden, with selection of dandelions, nettles, docks, couch grass, brambles, bindweed & horsetail. The triffids had blocked the light so less was growing under them.

Possibly horse radish?

Looks a bit like a Teazle.i let one grow in my garden, it was huge and looked magnificent. The dried seed pods are very decorative. Now I’m forever removing the seedlings!
They are very tough, but do pull up cleanly.

Yes, teasel. If you let it grow and flower, then cut the stems when the seeds are ripening, it should die - it's a biennial, grows one year and builds up energy stores, then flowers the next and dies. You're basically frustrating it, causing it to throw up new flowering spikes, which is why it's a clustered mess instead of the statuesque thing it normally is.

Yes, a teazle. The seed heads in winter are great for wildlife (although that does mean you can expect lots of seedlings in the following spring).

They had just been left to own devices. So given I've now cut before it flowered & seeds again, as a biannual it should die off?

There was small knee high dried teasel seedhead but I didn't see what plant looked like. Sorry birds & bees

I'm growing teazle ( deliberately) this year for next years goldfinches. But mine are teeny tiny compared to yours!

So given I've now cut before it flowered & seeds again, as a biannual it should die off? Yes, but not until the winter. Unless the fact that you haven't let it flower means it'll hang on to try again next year.