Brasenia

Brasenia is a small genus of aquatic flowering plants in the family Cabombaceae. It comprises Brasenia schreberi, the best known species, and a few related taxa. Commonly called water shield, the plants are perennial and aquatic, with a creeping rhizome that anchors them in soft substrates of ponds and slow-moving waters.

Description and morphology: Brasenia plants bear two leaf types. Floating leaves are rounded to shield-shaped and a few centimeters in diameter, featuring a translucent central area or window that allows light to reach tissues beneath. The petiole attaches near the center of the leaf on the underside. Submerged leaves, when present, are narrow and less conspicuous. Flowers are small, usually pale or white, and borne on short stalks above the water surface.

Habitat and distribution: Brasenia schreberi is native to temperate regions of the Northern Hemisphere, including parts of North America and Eurasia. It inhabits still or slow-moving freshwater environments such as ponds, marshes, and lake margins, often forming floating mats.

Ecology and reproduction: The plant can shade underlying vegetation as it mats on the water surface. It reproduces vegetatively through creeping rhizomes and stolons, and produces small, inconspicuous flowers in summer. The fruit is a capsule containing seeds.

Use and status: Brasenia is sometimes grown in freshwater aquaria and pond plantings for its distinctive leaf windows and shading effect. In some regions it is native and not considered invasive, while in others it can spread and influence local aquatic communities.