Iron stick yam is called iron stick yam because it is long and straight and resembles an iron rod. Iron stick yam is relatively short and thin, so the market is usually sold whole, which is different from the rest of the yam, need to be cut into several sections to sell, to a certain extent, but also more fresh. The "hairy eye" of the Tiezhi yam is relatively large, the burrs are relatively long, and the outer skin is darker in color, sometimes with purple spots. The outer skin is darker in color, sometimes with purple spots, and often has a large head and a small head, as if it were dragging a long, thin tail. Sometimes the tail may also take up half of the length, it is not like the common yam, the thickness is relatively uniform.