marshwort 
noun
A white-flowered plant of the parsley family which grows beside streams and in boggy areas.
- Genus Apium, family Umbelliferae: several species.
- Marshwort is a bottom-rooted perennial water lily-like plant.
- As its name suggests, creeping marshwort is a low-growing plant. The leaves are toothed with a single large cleft, and the plant sends out runners which creep low to the ground or slightly below the surface.