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 small family, largely of the southern hemisphere and largely aquatic (including all of our species). The submersed leaves in all our species (except one essentially leafless Myriophyllum) are pectinate, i.e., with a straight central axis and simple filiform lateral segments on both sides, like a 2-sided comb. Other aquatics with dissected leaves may have them forked dichotomously (Ceratophyllum) or more irregularly branched (Ranunculus, Utricularia, Bidens beckii), but the only other species with a straight central axis is Rorippa aquatica; it has alternate leaves with the lateral segments usually further divided.

1. Leaves all or mostly whorled (or nearly so), deeply pectinate, or (in M. tenellum) essentially absent (but alternate); flowers mostly unisexual, 4-merous, in axils of submersed deeply pectinate leaves or (most species) of emersed alternate or whorled bracts.


1. Leaves all clearly alternate, serrate to deeply pectinate; flowers bisexual, 3-merous, in axils of emersed alternate leaves.



MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. February 1, 2023.