Udo is a Japanese vegetable that is also known as Aralia elata. It is a perennial plant that grows in the wild and is native to Japan, Korea, and China. Udo has a thick stem and large leaves that are used in many traditional Japanese dishes. The root of the plant is edible and is often used in soups and stews. Udo is also known for its medicinal properties and is used to treat a variety of ailments.