Rootstock is a term used to refer to the underground part of a plant, such as its roots, rhizomes, and tubers. RHIZOME is a 7-letter word meaning an underground stem that sends out roots and shoots from its nodes. GINGER is a 6-letter word referring to a widely used spice made from the root of the GINGER plant. TARO is a 4-letter word referring to a tropical plant whose edible root is used in many dishes. ORRIS is a 5-letter word referring to the root of the iris flower, which is used to make perfumes and medicines.