Heteranthera dubia (Water Star-grass)
|Also known as:||Grass-leaf Mud-plantain|
|Family:||Pontederiaceae (Water Hyacinth)|
|Habitat:||sun; quiet waters, sandy or muddy shorelines and flats, stream banks|
|Bloom season:||July - October|
|Plant height:||1 to 2 inches (terrestrial)|
|Wetland Indicator Status:||GP: OBL MW: OBL NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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A single yellow, spidery flower on a stalk-like tube up to 4 inches long when plants are submerged, shorter on land-locked plants. Flowers are ½ to ¾ inch across with 6 narrow tepals (3 petals and 3 petal-like sepals). In the center are 3 thickly inflated stamens and a single style.
Leaves and stems:
Leaves are simple and alternate, narrow and flat with blunt tips, ribbon-like with or without a few parallel veins of equal prominence, 1/10 to ¼ inch wide and up to 5½ inches long when submersed, much shorter and thicker when emersed (above water). When the stem is buried in the sand or muck, leaves may appear almost basal, in a rosette around the flowering stem. Stems are slender and branching, typically submersed in water or buried in the sand or mud along the shore, rooting at the nodes and may create dense colonies.
Few people think of looking for wild flowers while at the beach or launching their fishing boat but this dainty aquatic species is often near at hand if not right underfoot. Dense carpets of fine ribbon like foliage, thickly dotted with small star-like flowers appear in later summer, especially as lakes experience their seasonal water level drop. Submersed plants in deeper water do not have the yellow flowers, but may have petal-less, self-pollinating flowers (cleistogamous) at the base of submersed leaves. When not flowering, plants look similar to Flat-stem Pondweed (Potamogeton zosteriformis), which has a prominent central vein on its leaves.
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Photos by K. Chayka taken at Glacial Lakes State Park, Pope County. Photos courtesy Peter M. Dziuk taken at Glacial Lakes SP and at South Center Lakes in Chisago County.
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