OverviewAppearanceHygrophila polysperma may be annual or perennial depending on location. The four angled stems grow from 4-8 in. (10-20 cm) tall and are often prostrate. Stems are slightly swollen above the nodes. It is native to temperate and tropical Asia, which includes China and India. It is cultivated in some areas.FoliageThe petiolate leaves are ovate to lanceolate with a smooth margin.FlowersHygrophila polysperma has tiny white flowers that bloom on terminal spikes from September to November.FruitThe fruits are oblong capsules with trichomes along the edge. Each fruit produces from 20-30 seeds. Fruits mature from October to January.Ecological ThreatHygrophila polysperma can become an invasive problem in some tropical and temperate regions outside of its native range. It is listed as a noxious weed in the United States. Hygrophila polysperma has only been reported in Alabama, Florida, Kentucky, South Carolina, Texas and Virginia. It has also been reported in Northern Mexico.