It's toxic to humans and pets alike. So pretty! I have one patch that is going to be spectacular sometime today or tomorrow.
I had to look up soursobs. You must be in Australia. I wish I still had chickens. I'm tempted to get a few, now that I have a mini Australian Shepherd. Give her something to do in my too small yard.
Yes, Australia, although I think the plant hails from southern Africa. Sounds like you'd have to remove all the periwinkle of you got chickens then!