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Water Stargrass
Heteranthera dubia

Native to Chesapeake Bay

  • Family - Pontederiaceae
     
  • Distribution - Water stargrass can be found in non-tidal freshwater areas of tributaries, and in streams, lakes and ponds. Water stargrass is rarely found in tidal areas, but has been identified in the upper tidal Potomac River. It grows primarily in clayey or calcareous soils, but is also reported to grow in gravel streams. Water stargrass can tolerate moderately eutrophic waters. A terrestrial form of water stargrass with waxy cuticle can also be found when low water levels strand plants on shore.
     
  • Recognition - Water stargrass has grass-like leaves with no distinct midvein. Leaves are arranged alternately on freely-branching stems, with the basal parts of the leaf forming a sheath which wraps around the stem. In summer, water stargrass produces yellow star-like flowers that protrude above the water surface. The terrestrial form also produces flowers, but branching of stems is reduced or absent and leaves are small or leathery.
     
  • Ecological Significance - Water stargrass has a conspicuous (bright yellow) flower that projects above the water surface during the summer. Unlike other bay grasses, water stargrass also has a terrestrial form that develops when low water levels strand the plant (the origin of its other common name, mud plantain).
     
  • Similar Species - The leaves of water stargrass are similar in appearance to those of the Naiads (Najas spp.).
     
  • Reproduction - Reproduction of water stargrass is by sexual and asexual means. During sexual reproduction yellow flowers are perfect and arise from a six-lobed spathe with a long thread-like tube. Flowers that do not reach the water surface remain closed and self-pollinate. Seeds are produced over the winter months and germinate in spring. Asexual reproduction occurs throughout the growing season by broken stem fragments. Water stargrass becomes dormant in winter, and stems and broken stem tips remain in the sediment until spring.
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