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Persicaria amphibia (L.) Delabare
Synonym: Polygonum amphibium
Coefficient of Conservatism: 6
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt P-Forb

Polygonum amphibium of Michigan Flora.

Lakes and ponds, permanent or ephemeral; river margins and quiet backwaters, marshes; “terrestrial” forms in drier ground nearby (or after lowering of water levels).

Variety amphibia is native to in the Old World; we have two native intergrading entities sometimes distinguished as varieties, as follows:

(a) var. stipulacea (N. Coleman) H. Hara. Stems prostrate, in water (up to 2 m deep) producing flowering shoots with floating leaves (superficially resembling those of a Potamogeton). Young terrestrial shoots with a ± horizontal green flange at the summit of the ocrea, seldom flowering. (Both types of shoot may be found on a single stem which extends from a terrestrial to an aquatic habitat.) Inflorescence ± ovoid or conic, 1.5–3 (–4) cm long. This variety occurs throughout the state.

(b) var. emersa (Michx.) J. C. Hickman. Stems ± erect, even when in the water. Floating leaves not produced. Ocreae without green flange. Inflorescence ± cylindrical, at least 3–8 cm long. This variety apparently occurs only very rarely north of the Straits of Mackinac in Michigan, though it is common in the southern Lower Peninsula.


Alger County
Allegan County
Alpena County
Antrim County
Baraga County
Barry County
Bay County
Benzie County
Berrien County
Branch County
Calhoun County
Cass County
Charlevoix County
    Including Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Clare County
Clinton County
Crawford County
Delta County
Dickinson County
Emmet County
Genesee County
Gladwin County
Gogebic County
Grand Traverse County
Gratiot County
Hillsdale County
Houghton County
Huron County
Ingham County
Ionia County
Iosco County
Iron County
Isabella County
Jackson County
Kalamazoo County
Kalkaska County
Kent County
Keweenaw County
    Including Isle Royale
Lake County
Lapeer County
Leelanau County
    Including Manitou Islands
Lenawee County
Livingston County
Luce County
Mackinac County
    Including Bois Blanc, Mackinac, Round Islands
Macomb County
Marquette County
Mason County
Mecosta County
Menominee County
Midland County
Missaukee County
Monroe County
Montcalm County
Montmorency County
Muskegon County
Newaygo County
Oakland County
Oceana County
Ogemaw County
Ontonagon County
Oscoda County
Otsego County
Ottawa County
Presque Isle County
Roscommon County
Schoolcraft County
Shiawassee County
St. Clair County
St. Joseph County
Tuscola County
Van Buren County
Washtenaw County
Wayne County


MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 7, 2022.