[daveNnorman]

anyone know what this plant is. It sprung up in my flower bed.

 

[JDGuy630]

Looks like mustard. but then again it doesn't. I would say go to your local gardening store and show somebody to see if they know.

 

[Chagrin]

Looks like mustard. but then again it doesn't.

I think your answer is as good as any.

If you've ever grown broccoli or cauliflower or let your radishes bolt then the younger leaves should look familiar. It's certainly a brassica and that covers a very wide variety of plants including rapeseed or mustard of which there are probably thousands of varieties. As a weed it would be called wild cabbage or field mustard.