Euphorbia amygdaloides var. Robbiae

As I'm cleaning up the borders in the back garden, I'm finding seedlings of this euphorbia here and there. I had heard it could be invasive as it freely self seeds but it's really not a problem.
We stayed out till 445 today. Getting a wee but lighter every day. I'm still weeding and cutting back and CH seems determined to dig out a huge alder seedling.