Senecio monoensis Greene, Leafl. Bot. Observ. Crit. 1: 221. 1906; S. filicifolius Greenman; S. lathyroides Greene; S. pectinatus A. Nelson

Herbage glabrate or glabrous. Calyculi: bractlets well developed (lengths, at least some, ¹ / 2 phyl-laries). Involucres campanulate. Phyllaries (± 13) ± 21, 7–10+ mm.

Flowering mostly summer–fall, less commonly spring. Open, rocky or sandy sites, especially desert basins and washes; 600–2000 m; Ariz., Calif., Nev., N.Mex., Tex., Utah; Mexico (Baja California).

Senecio flaccidus var. monoensis intergrades with var. douglasii and with var. flaccidus in areas of range overlap.