381 Sparganium emersum Rehm.

Syn.: S. simplex Huds.

This species is widely distributed in Eurasia. Further, the closely related S. multipedunculatum (Morong) Rydb., the American counterpart, and S. stenophyllum Maxim. in SE. Asia, Australia and New Zealand are also tentatively mapped (within the map area). S. emersum and S. multipedunculatum have together a circumpolar distribution (Hultén, Circumpol. I, p. 162 and map 153).