Herbs annual, often tinged purple-red, usually appearing conic, 10-40 cm tall, glabrous. Stem erect, terete or with colored ribs, glabrous or slightly glandular pubescent, much branched. Petiole short; leaf blade linear to narrowly lanceolate, to 7 × 1 cm, base attenuate, merging into petiole, margin entire to indistinctly erose-dentate, apex acute to acuminate; midvein yellow-white. Compound dichasia borne in leaf axils from near base of plant and on upper part of branches, apical branchlets of inflorescence acicular. Flowers not pedunculate, bisexual. Perianth segments 5, spreading in fruit, narrowly elliptic, slightly fleshy abaxially, margin membranous, apex obtuse or abruptly acute. Utricle depressed, orbicular; pericarp pellucid, adnate to seed. Seed horizontal, depressed, ca. 1 mm in diam., rim margin truncate or with a rib. Fl. Aug-Sep, fr. Oct.
Stems erect, [very bushy-branched] profusely branched from base to ± simple, [0.4-]0.7-2.5[-5] dm, glabrous or with scattered inflated hairs and uniseriate nonglandular trichomes, especially towards base. Leaves non-aromatic; petiole to 0.4 mm; blade [0.8-]2.8-3.4[-4.1] × 0.1-0.3[-0.6] cm, base attenuate, margins entire (to occasionally shallowly erose-dentate) }, apex acute, mucronate, glabrous adaxially. Inflorescences a terminal thyrse, 2.2-4.5[-13] cm, or lax, pyramidal cymes, bearing flowers almost from base; bracts absent. Flowers: perianth segments 5, distinct nearly to base, distinct portions obovate to elliptic or ovate, with low tubercle or sometimes keeled abaxially, 0.5-0.7 × 0.3-0.4 mm, apex obtuse to subacute, glabrous, loosely covering fruit at maturity; stamens 5 (or absent in pistillate flowers in distal portion of inflorescence); stigmas 2. Achenes subglobose; pericarp adherent, membranaceous, finely granular. Seeds subglobose, 0.5-0.8 × 0.4-0.5 mm, margins rimmed; seed coat smooth.