Also known as Greater Water Dock; formerly Rumex orbiculatus.
Pronounced: ROO-meks brih-TAN-ih-kuh
A tall native dock of wet ground, with long leaves and branching clusters of small flowers that develop into papery fruits.
Fruiting stems at Chiwaukee Prairie, Wisconsin. Select a photo to enlarge.
Family: Polygonaceae · buckwheat family
Bloom: June–July in the Upper Midwest
Height: about 3–6 feet
Light: sun to partial shade
Soil: moist to wet
Habitats: marshes, fens, shores and wet swales
Also known as: Greater Water Dock; formerly Rumex orbiculatus
Photo identification: These eight Chiwaukee Prairie photographs are a probable match for Great Water Dock. Confirmation requires checking all three grains and the stalk joint on individual mature fruits.
Look for a stout, hairless stem and long, narrow lower leaves. The lower leaf margins may be fairly flat or broadly wavy; upper leaves become smaller. Leaf shape alone is not enough to separate similar docks.
Mature fruits are surrounded by three broad, rounded to egg-shaped valves. In R. britannica, each valve bears a grain, with all three grains approximately equal in size. Examine several intact fruits from multiple angles.
Search moist to wet openings, marsh edges, fens and shoreline vegetation. Flowers appear in early to midsummer; the persistent fruit clusters make docks conspicuous later in the season.
Native to Canada and parts of the north-central and east-central United States, including Wisconsin and Illinois. This guide uses Rumex britannica; older references may use Rumex orbiculatus.
The papery structures are persistent flower parts called valves. The raised grains sit on their outer surfaces; they are not exposed seeds. A single three-sided achene is enclosed within the three valves.
For a useful identification view, photograph one intact mature fruit from several angles, including its narrow stalk and the joint near the stalk’s base.
Use mature fruit shape, the joint on its stalk and the lower leaves together. Red fruit color alone does not distinguish these species, and both Great Water Dock and Pale Dock can have three similarly sized grains.
Rumex britannica · Native
Valves: broadly rounded to egg-shaped, usually with blunt or slightly pointed tips.
Fruit stalk: slender; its joint is barely evident, rather than distinctly swollen.
Lower leaves: long and narrow, commonly 20–55 cm long, with flat to gently wavy edges.
Rumex altissimus · Native
Valves: broadly triangular to egg-shaped with a distinctly pointed tip.
Fruit stalk: relatively thick, with a swollen joint.
Lower leaves: typically shorter and proportionally broader, often 10–15 cm long and widest below the middle.
Rumex crispus · Non-native
Grains: usually conspicuously unequal in size.
Fruit stalk: has a more conspicuously swollen joint.
Lower leaves: typically have strongly crisped, curled margins. Combine this clue with the mature fruits.
Explore related docks and other native wildflowers, then practice recognizing plants in the wildflower quiz.
