Plant ID please

[BuddingGardener2017]

This just appeared in my border - it grew pretty quickly and I didn't plant it so I'm sure it's a weed, it just doesn't look like any of the wildflowers weeds around it! Any ideas?

It's Euphorbia lathyris - aka Caper spurge. Well-known for popping up out of nowhere, and definitely in the weed category. Pull it up before it seeds everywhere, but use gloves as Euphorbia sap (which is a milky latex) can be an irritant.

Thanks, that's good to know. I'll get my gloves out!