A vining perennial Yam that is hardy to Zone 5. It is indigenous to the mountains of Japan and Eastern China, where it is commonly eaten. By year three the plants host 9' vines that produce gallons of "Yam-berries". These are chickpea to almond sized tubericles that grow on the vine. You can harvest roots without ever having to dig up the soil! These plants are considered highly medicinal in the orient. They are edible raw or cooked. When raw they have a crispy yet mucilaginous texture that is soothing to soft tissue... this "slimy" texture helps make very fluffy mashed Yams. Known for making MASSIVE Yams that reach deep into the soil.
Long slender twining vines host delicate heart shaped leaves that have a deep shade of green. The vines host white trumpet shaped flowers that smell wonderfully like cinnamon. Great climber for making summer shade on the porch. The roots can grow 3' feet deep into the soil.
Tuber: The long tuber is delicious mashed. The baked roots also feature a wonderful texture. It is good put into soups shortly before they are finished (in its fresh state or after being dried into slices). It can be shredded into a paste that is mixed with wasabi and soy sauce and drank like a shot or used as a sauce.
Tubericles: These can be used much like the root can. Thaey are good when roasted in olive oil or boiled then salt and butter added.
Place tuber so the length is parallel to the soil surface. Place it 1" - 2" beneath the soil. If the tuber has a bend in it or a "foot" then you will orient it downwards into the soil. Planting it this way will prevent you from having to dig so deep to harvest all of the tuber. Alternatively you can plant it straight down for a straighter root. You can plant at 8" spacing, probably even less. Most growth is downward and the vines will crawl on eachother anyways so it is not a big problem to have them close (this makes it so they can share a trellis). Build a raised mound and plant the tuber on top. This will make it easier to dig it up when the time comes. Place a bamboo stake next to the crown tip of the tuber immediately after planting. Alternatively you can build a trellis when it starts to sprout up but the quicker you give it something to grow up, the more growth it will put on.
Keep them evenly moist. Thick mulch is a good way to keep the weeds from growing up into the vines. You can also use black plastic mulch. If you do not want to use mulch then do frequent hand weeding or use a scuffle hoe. It is irritating to weed the plants once the vines and weeds intertwine. Hardy Yams like full sunlight but do fine in partial shade, however they do not like excessive heat so if you have intense sun then it may be best to plant in partial shade.
The root is tender and easily broken so do not pry too hard to extract if from the soil. I like to use a nursery spade to jab and lift the surrounding soil. Once I have gone all the way around the plant I will dig a small hole on one side. I then dive my shovel as deep as it will go into the bottom of the hole. I then use the shovel's leverage to pry the plant up while holding the vegetation's crown. Planting 1 year old roots horizontally in mounds makes this process much easier. If you harvest the root you can plant back the top 6", keep the tuber and plant the crown.
Monitor the "Yamberries" for the right time to harvest. Do not wait until they fall off extremely easy or you might miss most of the crop. They should be removable with the slightest of a bumb. For harvesting the aerial tubericles you can pick them like berries or place a tarp below the trellis and knock off the tubericles by gently hitting the plants/trellis.