Lemna trisulca (Star Duckweed)
|Also known as:||Ivy-leaved Duckweed, Forked Duckweed|
|Habitat:||sun; quiet water to 4+ feet deep; lakes, ponds, creeks, rivers, ditches|
|Bloom season:||June - July|
|Plant height:||less than 1 mm|
|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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Plants rarely flower, but will float on the water's surface when they do. Flowers are contained in a lateral pouch, lack petals or sepals and have 2 stamens and a single style.
Leaves and stems:
Leaves, known as fronds, are 3 to 15 mm (to ½+ inch) long, 2 to 3.5 times as long as wide, narrowly egg-shaped to oblong-elliptic, blunt to rounded at the tip, often with a few minute teeth at the tip end (magnification required), and tapering at the base to a flat stem. Color is usually green, sometimes purplish. A frond may have a single, thread-like root up to about 1 inch long, though roots may be absent altogether.
Branched chains are formed with offshoots from a frond, which then offshoots another one or two stems and fronds and so on, a single chain having up to 50 fronds. Vegetative plants float just below the water's surface, not on the surface, and often form dense, tangled masses with thousands of chains.
Like the rare flower, fruit—a tiny seed less than 1 mm long—is rarely produced.
Star Duckweed is very common in Minnesota and not likely to be mistaken for any other species; the leaf shape and branching chains are quite distinctive. It may be overlooked since it is rarely seen floating but there is no mistaking it once you get a closer look. Like other Duckweeds, it's found in the quiet waters of lakes, ponds and slow-moving streams.
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Photos by K. Chayka taken in Anoka County.
Have you seen this plant in Minnesota, or have any other comments about it?