Seedling
Cotyledons elliptic, attached at 180 degrees from each other when seen from above. True leaves alternate, elliptic to lanceolate, with matted hairs on undersides of first 5 to 7 leaves. Papery sheath around stem where leaves join to it.
Mature plant
Stems erect or ascending to prostrate in open areas, branched, usually 1-1/2 to 4 feet tall at maturity, but can grow up to 6 feet. Swollen nodes at leaf axils where stems are encircled by a membranous sheath. Upper edge of sheath has minute bristles, only seen under magnification. Lower stems smooth, hairless; upper stems rough or gummy.
Leaves alternate, elliptic to lanceolate, 1 to 6 inches long, smooth edges, bottom 5 to 7 leaves hairy, matted underneath. Upper leaves usually hairless, with round, yellow, glandular dots underneath, leaving a yellow smudge when rubbed over a white paper. Leaves narrow into stalk, sometimes have a dark splotch marking in center.
Root structure description
Taproot, branched.
Flowers
Pink to white to green, without petals, in dense, spikes 1/2 to 4 inches long, at stem ends and in leaf axils. Green smartweed flowers in shorter, wider spikes than pale smartweed. Flowers July through September. Seeds lens-shaped, black shiny.
