This plant has appeared in my friend's garden for several years. Blooms purple, followed by the spiny seed pod. Leaves appear to be shaped like oak trees. I'm located in southeastern Wisconsin. Thanks for any ideas!
SOLVED: Spiny seed pod - oak-like leaves
I would 2nd that since I had one in Florida. I'm surprised it's growing that far north.
It's an annual so why wouldn't it grow that far north? Don't eat it but it enjoy it as an attractive flowering shrub for the summer. We don't eat holly berries or azaleas (both toxic) plus so many more plants. Remove the ones you don't want. I always let a couple grow to keep it as a self seeding annual.
Doubles are fancier but not as reliable for being self seeders.
It grew all year round for us and we just found that there are people growing brugmansia in our area which we had all year round too. Hearing that if left outside they die down and grow back is new to us. Thus normally it is not a annual. We had always considered it a tropical.