(6) ... Grows in Whiting's Pond, Columbia county, and in Botany Pond, three miles east of Albany. I have watched this and the two preceding species several years, and am satisfied, that they are distinct. Finding this to be a new one, not var. natans of Mx. I give it a new name [(6) = P. amphibium, var. natans, 3d. ed. Manual, and var. aquaticum, T(orrey).]