Senecio ertterae is a species of flowering plant in the aster family known by the common name Ertter's ragwort. It is endemic to Oregon in the United States. This annual herb grows 20 to 50 centimeters tall, sometimes reaching 60 centimeters or more. The leaves and stems are slightly succulent. The lance-shaped or spatula-shaped leaves are borne on winged petioles. The inflorescence is a cyme-shaped array of several flower heads. The yellow ray florets are each about half a centimeter long. Flowering occurs in July through October.