(a) Rue is the perennial herb of several species of Ruta (Ruta montana L., Ruta graveolens L., Ruta bracteosa L., and Ruta calepensis L.). The leaves, buds, and stems from the top of the plant are gathered, dried, and then crushed in preparation for use, or left whole.(b) The ingredient is used in all categories of food in accordance with § 184.1(b)(2) of this chapter at concentrations not to exceed 2 parts per million.(c) Prior sanctions for this ingredient different from the uses established in this section do not exist or have been waived.43 FR 3705, Jan. 27, 1978