Annuals, 18-70(-90) cm (delicate or robust, mostly glabrous). Stems usually erect (tufted-pubescent at nodes). Leaves sessile; blades linear-lanceolate to lanceolate, 30-90 × 6-22 mm, bases barely connate, margins strongly to weakly serrate or spinulose-serrate. Heads (10-)15-100+, in tight subglomerules in corymbiform arrays. Calyculi of 2 linear-lanceolate bractlets 1-3 mm. Involucres urceolate or oblong, 6-7 mm. Phyllaries 3, elliptic, obovate, or oblong-obovate. Ray florets 0 or 1; laminae yellow, ovate, 1.5-2.5 mm (apices notched). Disc florets 5-6(-8); corolla tubes 0.8-1.3 mm, throats funnelform, 1.2-1.7 mm. Cypselae oblanceolate, linear, or oblong, 2.8-3.6 mm (those of rays longer by ca. 0.2 mm); pappi 0. 2n = 36 (18). Flowering May-Nov. Saline soils, lake, pond, stream margins, flood plains, and disturbed pastures; 1000-1800 m; Ariz., Colo., Kans., Mo., N.Mex., Okla., Tex., Utah. Flaveria campestris is distinguished by subglomerulate capitulescences with 5-6(-8) florets per head, subtended by 3 leafy bracts, keeled phyllaries, and linear-lanceolate leaves with serrate or spinulose-serrate margins, and its distribution. The prevalence of F. campestris fluctuates greatly from year to year, generally depending on the existence of wet, saline habitat.