Williamsonia is a genus of plant belonging to Bennettitales, an extinct order of seed plants. Within the form classification system used in paleobotany, Williamsonia is used to refer to the female seed cones, which are associated with plants that also bore the male flower-like reproductive structure . Plants associated with this reproductive structure include the cycad-like Williamsonia sewardiana from the Early Cretaceous of India, as well as the woody shrub from the Late Jurassic of Japan.