Herbs, perennial, annual in colder regions, erect or ascending, dark green or glaucous, 2–9 dm. Stems erect, green to reddish, often profusely branched from base, slightly woody at base; branches ascending or spreading, not decumbent, slender. Leaves ascending or spreading; blade narrowly linear, planoconvex to semiterete, 7–50 × 0.8–1.8 mm, apex acute. Glomes in usually dense, branched, compound spikes, 1–3-flowered; spike ascending, 1–12 cm, slender; bracts shorter than leaves, 2–7(–12) × 2–4 mm. Flowers bisexual; perianth ± irregular or zygomorphic (segments slightly to strongly unequal), 1.2–2.5 mm diam.; perianth segments thin, at least one segment abaxially rounded and keeled and/or distally hooded, apex acute; stigmas 2(–5). Seeds dimorphic; lenticular, 1–1.8 mm diam., with seed coat black, finely reticulate, shiny; or flat, 1.5–2.6 mm, with seed coat brown, dull. 2n = 54.
