A stiff, medium to tall plant growing up to 100cm with a straggly appearance. The leaves are lanceolate and deeply serrated occurring in opposite pairs up the square stem. In the axils of the upper pairs of leaves are dense whorls of small white four lobed flowers (3 to 5mm) with tiny purple dots and two protruding stamens. The flowers have five long pointed sepals which are fused at the base into a bell-shaped calyx.