Floating bur-reef

What you see on the surface of the lake is not a seaweed but a flowering plant with long, narrow leaves that float on the water like shimmering ribbons. The bur-reef lives in the calm, cold, shallow waters of mountain lakes and ponds. Underwater, it has stems filled with nutrient reserves: known as rhizomes.
As the lake is gradually filled in with earth, the bur-reef population is expanding by bringing in its stems and withered leaves every winter.