Senecio vulgaris is an erect herbaceous annual growing up to 16 inches (45 cm) tall. The inflorescences usually lack ray florets, the yellow disc florets mostly hidden by the bracts giving the flowers an inconspicuous appearance.
Leaves and stems: Upper leaves of Senecio vulgaris lack petioles and are sessile, lacking their own stem (petiole), alternating in direction along the length of the plant, two rounded lobes at the base of the stem (auriculate) and sub-clasping above. Leaves are pinnately lobed and +2.4 inches (61 mm) long and 1 inch (25 mm) wide, smaller towards the top of the plant. Leaves are sparsely covered with soft, smooth, fine hairs. Lobes typically sharp to rounded saw-toothed.
The hollow stems branch at the tops and from the base. Stems and leaves can both host the Cinerarea leaf rust.