Proserpinaca palustris L.
Common Name: MERMAID-WEED
Coefficient of Conservatism: 6
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt P-Forb

Wet shores and banks, shallow water of ponds and streams, interdunal pools and swales, sedge mats, ditches; often in rather alkaline habitats.

This is a remarkable species in its variable leaf forms, which have been the subject of extensive physiological investigation. Most recently, both photoperiod and submergence have been demonstrated to play major roles in its heterophylly. Submersed shoots always produce dissected leaves, while aerial shoots produce dissected leaves under short days but simple leaves under long days (e.g., as summer progresses). High light intensity and high temperature, however, can at least partly counteract the effects of submergence. Since these plants tend to grow in areas of fluctuating water level (often shallow ponds, swales, and ditches), the series of leaf forms, including transitional states, can be quite varied on a single stem.

Even vegetative, completely submersed, dissected-leaved plants can be readily distinguished from Myriophyllum by the consistently alternate arrangement of the leaves and their relatively broader rachis; the internodes usually bear glandular-looking blackish flecks or spicules.

Locations

Allegan County
Alpena County
Benzie County
Berrien County
Cass County
Charlevoix County
    Including Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Clare County
Clinton County
Emmet County
Hillsdale County
Huron County
Ingham County
Jackson County
Kalamazoo County
Kalkaska County
Kent County
Keweenaw County
Lake County
Leelanau County
Lenawee County
Livingston County
Mackinac County
    Including Bois Blanc, Mackinac, Round Islands
Macomb County
Midland County
Monroe County
Muskegon County
Newaygo County
Oakland County
Otsego County
Ottawa County
Presque Isle County
Roscommon County
Schoolcraft County
St. Clair County
Tuscola County
Van Buren County
Washtenaw County
Wayne County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 18, 2017. http://www.michiganflora.net/species.aspx?id=1431.