An observational study of Potamogeton natans.

Abstract

Potamogeton is a cosmopolitan genus with 100 species (Gleason and Cronquist 1991) 33 of which occur in Michigan. Gleason and Cronquist place it as a single genus in Potamogetonaceae, whereas others include such genera as Zostera, Ruppia, Zannichellia, and Najas. Gleason states than the name came from Potamogeiton, an ancient Greek name of a water plant, and Fernald states the potamos is the Greek word for river, and geiton, the Greek work for neighbor. P. natans can generally be described as a non-arctic circumpolar plant with brownish-green floating leaves chordate at the base. Its submerged leaves are petiole-like. The sessile flowers are whorled in dense spikes and have four green tepals, four stamens, and four ovaries. As they mature into achenes or nutlets the spike elongates. The fruit is green, and turns brown when ripe. The achenes float and thereby may be water dispersed, but are also wildfowl distributed via ingestion. P. natans can also reproduce vegetatively through rhizomes and tubers which much of the literature describes as having red spots on them. It can also be dispersed by adhesion of parts to waterfowl. P. natans is widespread in Michigan and occurs in lakes, ponds, ditches, rivers and bogs. It has been collected in all but 14 counties.