Lythraceae

Upright perennial non-woody (herbaceous) plants and sprawling woody shrubs with simple, entire, opposite leaves (less often alternate and spiral, or whorled), many species occurring in aquatic or semi-aquatic habitats and having a well-developed floral tube (hypanthium); styles and stamens of various lengths, e.g., long styles and short stamens or vice versa, helping to ensure cross-pollination.

Flower arrangement varied, but often in clusters (cymes) where leaves or bracts join the stem (axils), Individual flowers usually producing both pollen and seeds, symmetrical in all directions (radially) or bilaterally, and with a flower tube shaped like a bell, cylinder or half of a sphere. Sepals usually 4 to 8, separate or slightly fused, often rather thick, meeting at the edges but not overlapping. Lobes of sepals alternating with appendages on the floral tube. Petals usually 4 to 8, separate, overlapping, crumpled in bud and wrinkled at maturity, occasionally absent. Stamens 4 to numerous, usually attached below the top of the flower tube, their stalks not equal in length. Carpels 2 to numerous, fused; ovary usually located above site of attachment of other flower parts (superior), rarely below (inferior): stigma more or less head-shaped. Flowers in different plants of the same species having 2 or 3 style lengths, and stamen lengths often varying inversely. Nectaries often at base of flower tube. Fruit usually a dry capsule. Seeds usually flattened and/or winged, seed coats with a many-layered outer skin, sometimes with hairs that expand and become glue-like.

Leaves mostly opposite, simple and entire, less often whorled or alternate, in some species partly expanded at the time of flowering. Side veins on leaves arising from both sides of a central vein (pinnate). Hairs various, sometimes silicified. Stipules typically reduced, commonly appearing as a row of tiny hairs.