Spikes of very small pinkish to green-white flowers, terminal and in leaf axils. Solitary flowers in lower leaf axils. Dull black nut. Leaves thin, lanceolate, short-stalked, with hot peppery taste. Sometimes turning orange/yellow in autumn. Branched hair-less stem, erect or straggling, red tinged. To 75cm.
Abundant except in parts of central Ireland. Damp ground and water-edges.