Home Polygonaceae Rumex

Rumex orbiculatus A. Gray

Common Name: GREAT WATER DOCK
Coefficient of Conservatism: 9
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt P-Forb

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.

B. S. Walters

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Counties
Alger
Allegan
Baraga
Barry
Benzie
Berrien
Calhoun
Cass
Cheboygan
Chippewa
Clinton
Crawford
Delta
Dickinson
Emmet
Gogebic
Grand Traverse
Gratiot
Ingham
Iron
Isabella
Jackson
Kalamazoo
Kent
Keweenaw
Lake
Lapeer
Leelanau
Lenawee
Livingston
Luce
Macomb
Manistee
Mason
Mecosta
Menominee
Monroe
Montcalm
Montmorency
Muskegon
Newaygo
Oakland
Ogemaw
Ontonagon
Ottawa
Roscommon
Schoolcraft
St. Clair
St. Joseph
Washtenaw
Wayne

Citation:
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. March, 16, 2025
https://lsa-miflora-p.lsait.lsa.umich.edu/#/record/2309