Ornamental Yam (Dioscorea dodecaneura)

Dioscorea dodecaneura, syn. Dioscorea discolor var. picta (Ornamental Yam, Variegated Monkey Ball Vine) it is perennial herbaceous climber (to about 3m = 10ft tall) native to Brazil, Paraguay and Argentina. It is extremely ornamental due to its variegated leaves with purple bottoms. 

The edible tubers of this species are gathered from the wild state and also it is sometimes cultivated as root vegetable. They are said to be edible raw or cooked (with an almond flavor). I have not tasted them yet due to I have not numerous tubers. The tubers can be stored in warm dry place without soil, or in dry soil in pots and when they are dormant they should be not watered. In my experience my plant has its own biological clock: it starts to re-sprouting in June and the aerial shoots dye in January. One plant creates a few tubers and can be propagated by them (replanted when dormant). It does not creates aerial bulbils. It likes much of sunlight (in sun the leaves are the most colorful), medium watering in growing period, and it is not frost hardy (suitable to zone 10 and warmer if grown in open garden or can be grown in pots and kept outside in summer and inside in cold period of year). It needs well drained fertile soil and is something drought tolerant. Easy to growing. Usually not infected by fungi diseases or insects (except mealybugs and aphids in my experience)..

The leaves are very ornamental

A first leaf in late spring

The leaves have purple bottoms

The tubers are edible (they are said to have an almond like taste - raw or cooked)

There are numerous other yams worldwide (both in tropics as in temperate areas) - if you have available tubers or seeds of any rare species please write to me