Plants perennial (possibly annual in some parts of its range). Stems prostrate or ascending, much-branched, 1.5-7 dm, densely puberulent. Leaves nonaromatic; petiole absent or indistinguishable from blade; blade oblong to elliptic, 0.6-4.5 × 0.1-1(-2) cm, base narrowly cuneate, margins deeply and irregularly pinnatifid with narrow, linear lobes, sometimes only dentate, apex acute to obtuse, glandular-pubescent abaxially. Inflorescences: lateral glomerules 1.8-3.5 mm diam.; bracts similar to cauline leaves. Flowers: perianth segments (4-)5, connate for most of their length, urceolate, tube with distinct reticulate veins, distinct portion 0.1-0.5 mm, margins dentate, apex rounded to broadly acute, accrescent and coriaceous with age, enclosing fruit; stamens 5; stigmas (2-)3(-5). Achenes obovoid; pericarp loosely adherent, membranaceous, with many yellow glandular hairs near apex, otherwise smooth. Seeds vertical, suborbicular to ovoid, 0.8-1.3 × 0.8-1 mm; seed coat smooth.
Fruiting mid summer-late fall. Waste ground, sandy shores and ballast dumps near coast; 0-700 m; introduced; Calif., Fla., Ga., Mass., N.J., N.Y., Oreg., Pa., S.C., Va.; South America; introduced widely throughout the tropical and warm-temperate regions of world.