Perennials or subshrubs, 50–120(–150) cm, strongly tarragon-scented or not aromatic; rhizomatous, caudices coarse. Stems relatively numerous, erect, green to brown or reddish brown, somewhat woody, glabrous. Leaves: proximal blades bright green and glabrous or gray-green and sparsely hairy, 5–8 cm; cauline blades bright green (gray-green in desert forms), linear, lanceolate, or oblong, 1–7 × 0.1–0.5(–0.9) cm, mostly entire, sometimes irregularly lobed, acute, usually glabrous, sometimes glabrescent (deserts). Heads in terminal or lateral, leafy, paniculiform arrays 15–45 × 6–30 cm; appearing ball-like on slender, sometimes nodding peduncles. Involucres globose, 2–3 × 2–3.5(–6) mm. Phyllaries (light brown, broadly lanceolate, membranous): margins broadly hyaline, glabrous. Florets: pistillate 6–25; functionally staminate 8–20; corollas pale yellow, 1.8–2 mm, eglandular or sparsely glandular. Cypselae oblong, 0.5–0.8 mm, faintly nerved, glabrous. 2n = 18.
