Bacopa rotundifolia, commonly known as the disk water hyssop or round-leafed water hyssop, is an aquatic perennial herb native to wetlands, pond margins, and slow-moving streams in the central Canada to Northeast Mexico. It typically grows in shallow water or saturated soil. The plant reaches a modest size, with round leaves that are 0 to 1 inch wide, featuring six longitudinal veins. From late summer to fall, it produces small, inconspicuous yellow-throated white flowers. While not particularly showy, the flowers add a subtle charm to water features.

Disk water hyssop is not commonly used in cultivation due to its invasive nature outside its native range, where it can outcompete native species and disrupt aquatic ecosystems. However, in controlled settings, it can serve as a ground cover in water gardens or naturalized pond settings. It requires full sun to part shade and thrives in wet, boggy soils. Care should be taken to prevent its spread into natural waterways. There are no popular garden cultivars of this species, and it is generally not recommended for widespread cultivation due to its potential to become invasive. It has been found to become invasive in waterways outside its native central U.S. range.CC BY-SA 4.0