[4] It can be found in shallow aquatic environments from Labrador and Newfoundland to Alaska, and south to Pennsylvania, Wisconsin, Michigan, Colorado, and California.

In Germany it is found in only two locations: the Feldsee and Lake Titisee, both in the High Black Forest.

Round white megaspores are about 480 micrometres (0.019 in) in diameter and are covered with spines.

Kidney-shaped microspores are about 26 micrometres (0.0010 in) long with smooth, fine spines.

braunii refer to the North American plants, but are often considered synonyms of Europe's I.