Gomphocarpus physocarpus, commonly known as hairy balls, balloonplant, balloon cotton-bush, bishop's balls, nailhead, or swan plant, is a species of milkweed. The plant is native to southeast Africa, but it has been widely naturalized. It is often used as an ornamental plant. The name "hairy balls" is an allusion to the swelling testicle-like follicles which are full of seeds.
