common mare's-tail —  Hippuris vulgaris {mare's-tail family — Hippuridaceae}
Flora of the Yukon Territory, Cody, p. 447a
 { 1/60 sec, f8.0} – {Hidden lakes, Whitehorse, Yukon} – {13/08/08 Wednesday, August 13, 2008; 3:02:54 PM}