Haloragaceae

Non-woody (herbaceous) aquatic plants.

Leaves alternate, opposite or whorled. Submersed leaves of all but one species deeply divided or compound, with a central stalk and simple thread-like segments projecting from both sides, like a 2-sided comb. Leaves reduced to tiny alternate scales or bumps on stem in Myriophyllum tenellum. Aerial leaves differ from submerged ones, but all usually have many lobes. Stipules none.

Flowers small, inconspicuous, often pollinated by wind, located on parts of the plant that have emerged from the water; may be solitary or 2 or 3 together in the axils of leaves or in spikes at the top of the stem. Each plant producing both pollen and seeds, in the same flowers in Proserpinaca, in separate flowers in Myriophyllum. Petals usually none; when present 3-4, small, fall off soon after flowering. Sepals 3 or 4, fused at base to form a tube, with separate lobes or teeth at top, persistent. Stamens 3-8. Carpels 3-4, fused to form 1 pistil; ovary located below point of attachment of other flower parts (inferior); styles 3-4, feathery. Fruit is either a small nut often with 4 lobes, or like a stone fruit.