Jay is taking an online class in growing vegetables from Ron Finley. One of the things he showed was how to grow a sweet potato. so Jay started growing a sweet potato in a jar. It is about ready to go into the ground. There are other ways to grow sweet potatoes. This is just the one Jay chose to try.
In NZ they are called Kumera .. they actually make am interesting house plant if left in the jar .. they climb everywhere.. Good luck hope he gets lots of tubers off this one..