Publication: Monatsber. Königl. Preuss. Akad. Wiss. Berlin. 1863: 435. 1864.
selected vouchers: WTU
Notes: Known in Washington from a single collection in eastern Washington.
FNA2: "Pilularia americana also has been reported from Alaska. I have seen no vouchers from Alaska, nor have I seen the Oregon vouchers. Because of its grasslike appearance and subterranean sporocarps, P . americana is probably overlooked and more common than records indicate. The telltale circinate vernation of the leaves is the best characteristic for distinguishing it from similar plants.
Pilularia caroliniana A. Braun, an invalid name, has been used for this species and may appear on specimens."