Air Potato Plant
Master Gardener friends have said, "Pull that thing up, it's a weed," but I've actually provided a little trellis for it to grow on.
This plant is part of a large genus of 600 plants named after the Greek physician, Dioscorides. There are about 10 of the species that are edible and cultivated. Many, though, are poisonous.
This plant, also called "air potato yam" or "aerial yam", is a vining plant which supposedly grows to three feet (ours is larger), has green heart-shaped leaves and produces (ugly) brown aerial tubers in late summer.
It is found in tropical Africa, Asia, Northern Australia, and the Philippines. It supposedly grows in Zones 10-12, but this one is growing on the border of zones 8 and 9.
It completely dies back in the winter and grows again from perennial roots.
Propagation is usually done by division, however, with patience, seed can be sown in the fall and in the spring.