I have a volunteer plant in my garden that looks interesting and is not a weed that I am familiar with. The leaves are oak leaf shaped and about the size of my hand. They are a fairly dark green but the stem has a reddish cast. New stems and leaves are growing in pairs on the stem at the base of each mature leaf. Can anyone suggest what it might be. I've lived here in Phoenix most of my life and I can't recall ever seeing this plant before. I can't decide whether to pull it, or encourage it. Since my beds are a mix of flowers, vines and vegetables an attractive volunteer here and there is not a problem, but I would like to identify it if possible. thanks