Description

Key Characters:

Growth Form: Annual herbs.

Stems: Stems 3–10 dm long, intricately many-branched, forming a round, bushy clump, with age breaking off and becoming a tumbleweed, glabrous or sometimes sparsely hirsute.

Roots:

Leaves: Leaves simple. Alternate. Blades narrow, linear, terete (cylindrical) when fresh, somewhat flattened when dry, 3–5 cm long, upper leaves usually only 0.5–0.8 cm long. Apex spine–tipped. Margins entire. Sessile. Stipules absent.

Flowers: Flowers in inflorescences1-flowered (rarely 2–3-flowered with lateral flowers mostly abortive); bracts alternate at maturity, ± abruptly narrowing into mucronulate-spinose apex. Flowers small, bisexual (perfect), each one subtended by 2 small bracteoles. Calyx (4)5-lobed, with enlarged membranous wings in fruit, 3–6 mm wide when well-developed, those of lowermost flowers often merely carinate. Corolla (petals) absent. Stamens usually 5; anthers dithecal, opening by longitudinal slits. Ovary superior, 2–3(–5)-carpellate, 1-celled, placentation basal; ovule 1; styles 2(3); stigmas 2(3), dry.

Fruit: Utricles flattened; enclosed by the calyx. Seeds 1 per fruit; horizontal; orbicular; black; shiny; 1.5–2 mm in diameter.

Ploidy: 2n = 36

Habitat: Along roadsides and in other disturbed areas.

Elevation Range: 36–1682 m.