Embryo with usually with 2 cotyledons. stem vasculature usually a eustele. Plants annual or perennial; terrestrial or aquatic; branched or unbranched; woody or herbaceous. Leaves usually not strap-like; if present forming a basal rosette or arranged variously along the branches; venation commonly reticulate. Roots present, with a ± well developed tap-root. usually 4—5-merous.