Perennials, 20-80 cm (not cespitose), pleasantly aromatic (fibrous-rooted, rootstocks relatively short, horizontal, layered stems sometimes sprouting). Stems 3-20+, erect, gray-green, usually simple, sometimes branched (bases woody), densely tomentose. Leaves cauline, bicolor (white and green); blades linear to lanceolate, 3-12 × 1 cm, margins usually entire, sometimes toothed or lobed, faces densely tomentose (abaxial) or glabrate (adaxial). Heads (peduncles 0 or to 2 mm) in mostly racemiform arrays 8-13 × 1-2 cm. Involucres campanulate, 4-5 × 4-5 mm. Phyllaries ovate-lanceolate (margins hyaline), densely to sparsely tomentose. Florets: pistillate 3-10; bisexual 8-26; corollas pale yellow, 1-2 mm, sparsely glandular. Cypselae ellipsoid, 0.5-0.8 mm, glabrous. 2n = 36.

Flowering mid summer-early fall. Alkaline flats, grasslands, barren areas, high plains; 500-1800 m; Alta., B.C., Man., Sask.; Idaho, Minn., Mont., Nebr., N.Dak., S.Dak., Wyo.

Artemisia longifolia appears to be more salt-tolerant than most species of the genus. It is closely related to A. ludoviciana.