Utricularia intermedia Hayne
Common Name: FLAT-LEAVED BLADDERWORT
Coefficient of Conservatism: 10
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt P-Forb

A circumpolar species, usually of alkaline waters: interdunal pools and wet flats, fens, marshes, ponds, rivers, lakes; may grow in water a meter or more deep, but thrives and flowers in shallow water.

The lower lip of the corolla is relatively flat (except at the base) compared with the lower lip in U. vulgaris, which has the sides turned down, giving it a strongly humped aspect. The spur in U. vulgaris is more conical (broad-based) and curved less strongly under the lip; the more slender spur in U. intermedia is ± closely pressed to the bottom of the lip, even into a concavity. These two common species, often growing together, can thus be easily identified without close examination when in bloom.

The bladders in U. intermedia are as long as 5 mm on some individuals, though usually they are 1–3.5 mm. In shallow water (or very recently exposed wet mud) the green leaves when dense often give a mossy appearance (though actually flat and fan-shaped in outline), while the bladder-bearing branches are buried in the substrate.

The mysterious U. ochroleuca R. W. Hartm. has been collected near the north shore of Lake Superior in Ontario, and may occur in Michigan. It has a spur about half the length of the lower lip; in U. intermedia it is about as long. The specimen could also be the even less well known U. stygia G. Thor.

Locations

Alcona County
Alger County
Alpena County
Antrim County
Baraga County
Barry County
Benzie County
Berrien County
Calhoun County
Cass County
Charlevoix County
    Including Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Crawford County
Delta County
Emmet County
Gladwin County
Gogebic County
Grand Traverse County
Gratiot County
Hillsdale County
Houghton County
Huron County
Ingham County
Iosco County
Isabella County
Jackson County
Kalamazoo County
Kalkaska County
Kent County
Keweenaw County
    Including Isle Royale
Lake County
Leelanau County
Lenawee County
Luce County
Mackinac County
    Including Bois Blanc, Mackinac, Round Islands
Marquette County
Mason County
Mecosta County
Montmorency County
Muskegon County
Newaygo County
Oakland County
Ontonagon County
Otsego County
Presque Isle County
Roscommon County
Schoolcraft County
Van Buren County
Washtenaw County
Wexford County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 13, 2017. http://www.michiganflora.net/species.aspx?id=1617.