Please try our next iteration of the Michigan Flora Online here. Beginning on February 1, 2023, will point to this new site.

The new site offers several benefits over the existing website, including real coordinate mapping, giving a clearer view of the density of documentation as well as more precision about plant distributions and their link to landforms. We will also have the ability to update species pages more regularly, both in terms of new collections and as more existing Michigan specimens are georeferenced. In addition, we have a better photo display, and offer indented keys.


A rather small family of aquatic plants, some of them marine and most of them native in warm or tropical regions. All of our species are dioecious, except some Najas, and, except for Najas, are pollinated at the surface of the water.

1. Leaves floating, blades orbicular with a ± cordate base.


1. Leaves submerged, linear.

2. Leaves very long and ribbon-like (mostly 3–11 mm wide and many times as long), in a basal rosette.


2. Leaves up to 6 (–12) cm long, opposite or whorled.

3. Leaves whorled, entire (to the naked eye).


3. Leaves opposite, minutely denticulate to visibly toothed.



MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. January 29, 2023.