• Lake Superior in a stormy mood. Photo copyright Craig Blacklock

    Pictured Rocks

    National Lakeshore Michigan

Freshwater Plants

Marsh marigolds bloom in bright yellow along a springtime stream.

Marsh marigolds along a stream

NPS photo

The phytoplankton of the inland lakes of Pictured Rocks National Lakeshore include at least 51 taxa of blue-green algae (Cyanophyta), dinoflagellates (Pyrrhophyta), yellow-brown algae (Chrysophyta), diatoms (Bacillariophyta), and green algae (Chlorophyta). Seasonal fluctuations occur in the relative densities of these unicellular plants.

Dominant taxa include the diatoms Asterionella formosa, Fragillaria intermedia, Aulocoseira islandica, and Tabellaria fenestrata and the blue-green algae Aphanizomenon flosaquae, Aphanocapsa rivularia, Chroococcus limneticus, and Lyngbya birgei. The filamentous green alga, Bulbochaete sp., is found attached to submerged logs in softwater Legion Lake. Diatoms of this acidic lake are typically benthic, and, due to limited dissolved silica, are not preserved in the sediments.

Did You Know?

Dune grass thrives on the Grand Sable Dunes near Grand Marais, Michigan, in Pictured Rocks National Lakeshore.

On October 6, 1972, ceremonies in Munising marked the establishment of Pictured Rocks National Lakeshore, America's first national lakeshore. To symbolically link the park's two gateway communities of Munising and Grand Marais, water was poured from two glass containers into a third. More...