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Water Stargrass

Heteranthera dubia

Water stargrass is a bay grass with long, grass-like leaves and distinctive yellow, star-like flowers along freely branching stems. It grows in the fresh waters of the upper Chesapeake Bay and tributaries throughout the Bay watershed.

Appearance:

• Long, grass-like leaves that grow alternately along freely branching stems
• Base of each leaf wraps around the stem
• In summer, has small, yellow, six-petaled flowers that project above the water’s surface

Habitat:

• Shallow tidal and non-tidal fresh waters
• Usually grows in clay or chalky sediment but is sometimes found in streams with a gravel bottom

Range:

• Ranges from the upper Chesapeake Bay to freshwater rivers, streams, lakes and ponds throughout the Bay watershed
• Has been recorded in rivers such as the upper tidal Potomac River and the Bush, Elk, Magothy, Middle and Sassafras rivers in Maryland

Reproduction and Life Cycle:

• Asexual reproduction occurs when stem fragments break off and overwinter at the bottom before growing into a new plant in spring
• Sexual reproduction takes place in summer when the plant flowers. Seeds form in late summer and autumn, then grow into new plants in the spring.

Other Facts:

• Gets its name from its yellow flowers, which look like tiny stars floating above the water
• Can grow on land if it washes ashore. The land-growing form has smaller leathery leaves and very few branches, but still produces the characteristic star-like flowers.

Sources and Additional Information:

• Underwater Grasses in Chesapeake Bay & Mid-Atlantic Coastal Waters by Peter W. Bergstrom, Robert F. Murphy, Michael D. Naylor, Ryan C. Davis and Justin T. Reel
• Life in the Chesapeake Bay by Alice Jane Lippson and Robert L. Lippson
• Chesapeake Bay: Nature of the Estuary, A Field Guide by Christopher P. White
• Bay Grass Key: Water Stargrass – Maryland Department of Natural Resources
• PLANTS Database: Heteranthera dubia – USDA Natural Resources Conservation Service

Places:

• Potomac River Water Trail – Washington, D.C. to Point Lookout, Maryland