common mare's-tail —  Hippuris vulgaris {mare's-tail family — Hippuridaceae}
Flora of the Yukon Territory, Cody, p. 447a
 { 1/64 sec, f3.4} – {Paddys Pond/Ice Lake, Whitehorse, Yukon} – {13/09/01 Thursday, September 13, 2001; 4:40:29 PM}