This is a close-up of Eurasian Watermilfoil (or just "milfoil"). It was just harvested from Lake Harriet in southwest Minneapolis. Several large harvesting machines, resembling pontoon boats, cut the milfoil underwater and collect in for disposal.

This invasive exotic plant is a nuisance in several Minneapolis lakes; it outgrows native plants, reaching the surface of the water and interfering with swimming and boating.