Heteranthera dubia (Water Star-grass)

Plant Info
Also known as: Grass-leaf Mud-plantain
Family:Pontederiaceae (Water Hyacinth)
Life cycle:perennial
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):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 6-petals

[photo of flower] 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: Leaf attachment: alternate Leaf attachment: basal Leaf type: simple

[photo of leaves] 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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More photos

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.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Debbie - St. Louis Park
on: 2014-09-09 09:48:24

I found this little gem on Meadowbrook Golf Course (closed for the season)along Minnehaha Creek in recently drained areas that were flooded earlier in the season.

Posted by: John Genet - NE Swift County
on: 2019-08-16 10:44:35

Photographed this flower on the banks of the East Branch Chippewa River about a mile south of Swift Falls, MN. A colleague who is a plant ecologist identified the plant in the field, so am confident of its ID.

Posted by: K. Chayka
on: 2019-08-16 14:03:02

John, it is not surprising you found it in a previously undocumented location. Aquatic plants haven't been surveyed as much as terrestrials, but the DNR's biological survey team is working on addressing that. I bet they will find this is more abundant than the current records indicate

Posted by: Brett W - Otsego
on: 2019-09-07 17:25:36

Found flowering along an island shoreline in Crow Wing State Park.

Posted by: Brett W - Hennepin county
on: 2020-07-22 10:20:58

Found flowering today along sandy shore of Mill Pond in Champlin.

Posted by: Aaron McGuire - Lebanon HIlls Regional Park - Holland Lake
on: 2022-07-23 21:46:40

Found flowering on muddy bank of Holland Lake. Dakota County. 7/21/2022.

Posted by: Benjamin Lundeen - County Ditch 42
on: 2023-02-01 12:31:52

Observed this plant while collecting aquatic insects from County Ditch 42, 7.5 miles Northeast of Wheaton, MN.

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