Rumex orbiculatus A. Gray
Common Name: GREAT WATER DOCK

Coefficient of Conservatism: 9
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt P-Forb
Rumex orbiculatus B. S. Walters

Moist to very wet ground or shallow water of peatlands, river margins, marshes, ponds, swales, and ditches.

One of our most distinctive species in its very late fruiting, often extremely large stature in wet places, raised position of the grain on the tepals, and absence of a swelling at the joint in the pedicel. Even young flowering plants of R. crispus and related species have the joint evident. There is also a subtle difference in leaf venation, the main lateral veins in R. orbiculatus continuing prominent farther from the midrib than in R. crispus (and others), in which they soon become weak, branched, and anastomosed. The basal leaves may be over a meter long. We are reluctant to adopt the name R. britannica L. for this species, given the complexities noted by Fernald (1945) and the fact that the name has not been typified.

Locations

Alger County
Baraga County
Barry County
Benzie County
Berrien County
Calhoun County
Cass County
Cheboygan County
Chippewa County
    Including Drummond Island
Clinton County
Crawford County
Delta County
Dickinson County
Emmet County
Gogebic County
Gratiot County
Houghton County
Ingham County
Iron County
Isabella County
Jackson County
Kalamazoo County
Kent County
Keweenaw County
    Including Isle Royale
Lapeer County
Leelanau County
Lenawee County
Livingston County
Luce County
Macomb County
Manistee County
Mason County
Mecosta County
Menominee County
Monroe County
Montcalm County
Montmorency County
Muskegon County
Newaygo County
Oakland County
Ogemaw County
Ontonagon County
Roscommon County
Schoolcraft County
St. Clair County
St. Joseph County
Washtenaw County
Wayne County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. September 17, 2014. http://www.michiganflora.net/species.aspx?id=2309.