I had noticed this pile of 'something' from a distance and was curious enough to stop and take a closer look as we drove around the lake. I expected it to be some kind of vegetation and was surprised to realize there were furry bodies in the vegetation. There seem to be two muskrats on this mound and there were two more on the ice at the edge of the hole adjoining the mound. Further off on the lake, there were more small holes in the lake and 4 more muskrats were evident, two at one hole, one at another, and the fourth further off on the ice. As we drove along the lakeshore, we spotted another pile of vegetation and more muskrats. I've added that second mound to this observation.
Today I learned that muskrats gnaw holes in the ice with their teeth and build dome-shaped mounds of marsh plants that cover these holes (with our warmish weather, the holes on this day extended further than the mounds). More info here:
https://northernwoodlands.org/outside_story/article/in_homes_on_ice_muskrats_endure_the_season
observation for the vegetation here:
https://www.inaturalist.org/observations/144244739
tubercle distinct from achene, surface appears smooth, bottom scale did not entirely circle culm, culms all greater than 10cm.
Ceratophyllum platyacanthum subsp. oryzetorum (Kom.) Les
presumed seedlings (submersed plants) were abundant;
Second pic is from Crowe and Hellquist (2000), Pontederia (above) and Sparganium (below). 3rd pic is my photo from leaf from submersed rosette like this one (left); Sparganium leaf (right)
Added 2nd and 3rd pics To further discussion below.
Based on branching of the leaflets this is Spiny Hornwort rather than coontail
This 4 headed cattails was one of many I observed this summer 2019 at Spring Lake Park in lower North Mankato, MN. What causes this?
Found floating in a single pile on the shore of Vadnais Lake. They are tuber-like and grow roots from the "eyes"