And it IS a member of the carrot family, Apiaceae :-)

If you dig it out now, and keep at it, you might be able to get rid of it in five or six years.

Aegopodium podagraria, no doubt! And yes, member of carrot fam. as mentioned!

Is the flower poisonous like h?

No. The plain green version of this was introduced to Britain by the Romans as a culinary vegetable. Thanks very much, Romans😒

the variegated cultivar tends to be somewhat better mannered, but it can selfseed and the babies tend to revert to the plain, green thuggish version

Head Donna’s advice. I had a small patch of this at a shady edge of my property 5 years ago (planted by the previous homeowners). I didn’t know any better and left it. It completely reverted back to all green and has nearly taken over my backyard (it has even outcompeted creeping buttercup). My covid hobby has been digging this out 😭

This plant is a very persuasive case for the use of RoundUp.

I maybe the only person on the planet that likes this plant :-) I have used it successfully a number of times but in a very controlled environment....no chance of escape and intentions for world domination. I've also never had it revert but have overseen the elimination of expanses of both the variegated form and the solid green mixed. I think the reversion is more likely to occur when the plant spreads unchecked.

Gardengal, I’m curious to know how you use this plant and also how you keep it controlled? I may have to accept to work with it instead of against. I’m also battling creeping bellflower, Japanese knotweed, and nightshade…goutweed is mild compared to these bozos!

Deal with the knotweed above all else ....