Vaccinium macrocarpon Aiton
Common Name: LARGE CRANBERRY
Coefficient of Conservatism: 8
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt Shrub

Characteristic of bog mats, persisting in some shade; interdunal swales and hollows, poor fens. Often forms dense stands ringing the open water of a bog pond.

Unlike the circumpolar V. oxycoccos, this is a strictly North American species. The leaf blades tend to be more elliptic-oblong or even slightly spatulate in comparison with those of our other cranberries. The leaves, flowers, and fruits average a little larger. Occasionally the two (usually ± opposite) bracts on the pedicels are ambiguous, e.g., relatively narrow and reddish in V. macrocarpon, resembling large ones of V. oxycoccos. Additional points of distinction in the field are these: (1) The stems in V. macrocarpon are usually prolonged well beyond the flowers or fruit, while in V. oxycoccos the flowers and fruit usually appear to be terminal or nearly so, without a prolonged leafy shoot. (2) V. oxycoccos blooms about a month earlier, generally in June or sometimes as late as mid-July in the Upper Peninsula; V. macrocarpon blooms in July, or sometimes as early as mid-June in southern Michigan. Our two cranberries are sometimes segregated as the genus Oxycoccus.

Locations

Alger County
Allegan County
Antrim County
Arenac County
    Including Charity Island
Baraga County
Barry County
Benzie County
Berrien County
Calhoun County
Cass County
Charlevoix County
    Only on Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Clare County
Crawford County
Delta County
Emmet County
Genesee County
Gogebic County
Grand Traverse County
Gratiot County
Hillsdale County
Houghton County
Ingham County
Iosco County
Iron 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
Marquette County
Mason County
Mecosta County
Midland County
Muskegon County
Newaygo County
Oakland County
Presque Isle County
Roscommon County
Saginaw County
Schoolcraft County
St. Clair County
Van Buren County
Washtenaw County
Wayne County
Wexford County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 11, 2017. http://michiganflora.net/species.aspx?id=1234.