Shallow water of small lakes, ponds, ditches, and streams.

A very local but distinctive species. The stipules are somewhat less fibrous than is often the case in P. friesii and P. strictifolius, and the winter-buds are quite different, being similar in texture to large ones of P. pusillus var. tenuissimus for example, and are borne at the ends of branches. The peduncle is short and the spike nearly spherical, as in P. foliosus, but there is no sharp keel on the much larger fruit. The leaves are very sharp, even bristle-like, at the apex.

Named after the prolific collector Ellsworth J. Hill (1833-1917), who first gathered the species in Manistee Co. in 1880. His collections are in many herbaria.