Senecio semicordatus Mackenzie & Bush, Rep. (Annual) Missouri Bot. Gard. 16: 107. 1905; S. pseudaureus Rydberg var. semicordatus (Mackenzie & Bush) T. M. Barkley

Plants 20–40+ cm (slender). Basal leaves: petiole lengths 1.5–2 times blades; blades broadly lanceolate to ovate, 20–40 × 10–20 mm, margins crenate. Heads 6–12 in open or slightly congested, corymbiform or cymiform arrays. Phyllaries 4–6 mm. 2n = 88, 126, 138.

Flowering early Apr–mid Jun. Damp areas and open prairies; 300–1500 m; Iowa, Kans., Minn., Mo., Nebr., N.Dak., S.Dak.

Variety semicordata resembles var. flavula; it grows in open prairies.