Hydrilla is a bay grass with whorls of tiny, toothed leaves along long, freely branching stems. It is an invasive species that grows in freshwater portions of the Chesapeake Bay and most of its tributaries.
Hydrilla is made up of long, freely branching stems with tiny, straight or lance-shaped leaves that usually have visible teeth along the edges. Leaves grow in whorls of 4 to 5 along each stem. Tiny, white flowers appear in late summer. Rhizomes grow along or just below bottom sediments. Roots and small, fleshy tubers grow from the rhizomes.
This grass grows in fresh waters, but has also been found in brackish waters. It does not need as much light as other bay grasses, so it can grow in more turbid areas.
Hydrilla is common in the upper Chesapeake Bay and in most freshwater tributaries. It is native to Africa, Australia and parts of Asia.
Migratory waterfowl feed on hydrilla.
Asexual reproduction takes place when plant fragments, tubers, roots and turions develop into new plants. Sexual reproduction occurs in late summer, when pollen from male flowers fertilizes female flowers. The seeds that form have about a 50 percent chance of growing into new plants.