Herbage usually tomentose (hairs whitish), sometimes unevenly glabrescent. Calyculi: bractlets minute or 0. Involucres cylindric or weakly campanulate. Phyllaries ± 13 (± 21), 5- 8+ mm.
Flowering mostly summer-fall, less frequently spring. Dry, open sandy or rocky plains, streambeds, and canyons; 800-2400 m; Ariz., Colo., Kans., N.Mex., Okla., Tex., Utah; Mexico.
Senecio flaccidus var. flaccidus intergrades at least to some extent with var. monoensis in areas of overlapping ranges; a case could be made for treating the two as distinct species, as done by A. Cronquist (1994).