Stems 0.5-4.5 dm. Fruiting bracteoles sessile, orbicular but not especially samaralike, compressed, (2-)3-4 mm, united to beyond middle, margin dentate to incised, teeth 0.5-1 mm. Seeds 1-1.5 mm. Flowering spring-fall. Saline creosote bush scrub, deserts; below 800 m; Ariz., Calif., Nev., N.Mex., Tex., Utah; n Mexico (Chihuahua, Sonora). The faces of the fruiting bracteoles are typically smooth, but in some plants of southern Arizona especially the faces bear a single sub-basal crest, or more commonly paired crests alongside the bracteole median. The cristae rise and fall not only within populations but on individual plants, as pointed out by H. M. Hall and F. E. Clements (1923), and apparently lack taxonomic value. A sterile collection from Brewster County, Texas (B. H. Warnock 409-T), has long-attenuate leaf bases, the expanded portion of the blade spatulate-oblanceolate to oval. It is tentatively placed here, but might represent some species from south of the Mexican border.