Species Profile - Rumex obtusifolius

Rumex obtusifolius L.

Common Name: Bluntleaf dock

Synonyms and Other Names:

Rumex obtusifolius var. obtusifolius L., Rumex obtusifolius spp. agrestis (Fr.) Danser, Acetosa oblongifolia (L.) Á. Löve & D. Löve, Rumex obtusifolius spp. sylvestris (Wallr.) Rech. f., Rumex obtusifolius var. sylvestris (Wallr.), Rumex crispatulus Michaux; R. rugelii Meisner Koch, bluntleaf dock, Broad-leaved dock, butter dock, cushy-cows, kettle dock, smair dock

Rasbak (commons.wikimedia.org) Copyright Info

Identification: This species is a perennial plant, glabrous or ± papillose especially on veins of leaf blades abaxially, with fusi-form, vertical rootstock. Stems erect, branched distal to middle or occasionally in distal 2/ 3, often with few flowering stems from rootstock, 60-120(-150) cm. Leaves feature ocrea deciduous to partially persistent at maturity; blades oblong to ovate-oblong, sometimes broadly ovate, 20-40 × 10-15 cm, usually less than 4 times as long as wide, base normally distinctly cordate, occasionally rounded, rarely truncate, margins normally entire, flat or undulate, rarely slightly crisped, apex obtuse or subacute. Inflorescences are terminal, occupying distal 2/ 3 of stem, usually lax and interrupted, narrowly or broadly paniculate, branches usually forming angle of 30-45° with first-order stem. Pedicels are articulated in proximal 1/3 or rarely near middle, filiform, 2.5-8.5(-10) mm, articulation distinctly swollen. Flowers occur in groups of 10-25 in lax whorls; inner tepals are ovate-triangular, deltoid or, occasionally, lingulate, 3-6 × 2-3.5 mm (excluding teeth), ca. 1.5-2 times as long as wide, base truncate, margins usually distinctly dentate, rarely subentire, apex obtuse to subacute, straight, teeth 2-5, normally at each side of margin, short-subulate or triangular-subulate, straight, 0.5-1.8 mm, or shorter than width of inner tepals; tubercle usually 1, sometimes 3, then 1 distinctly larger, smooth. Achenes are brown to reddish brown, 2-2.7 × 1.2-1.7 mm. 2n = 40.

Size: up to 150 cm

Native Range: Eurasia and Asia.

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This map only depicts Great Lakes introductions. Click here for Great Lakes region collection information

Great Lakes Nonindigenous Occurrences: The earliest record of R. obtusifolius in the Great Lakes Basin is first reported in 1840. Now widespread in the Great Lakes region, including Illinois, Indiana, Michigan, Minnesota, New York, Ohio, and Pennsylvania, as well as in Canadian Great Lakes provinces.

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Rumex obtusifolius are found here.

State/Province	First Observed	Last Observed	Total HUCs with observations†	HUCs with observations†
IN	1896	2008	4	Little Calumet-Galien; St. Joseph; St. Joseph; St. Marys
MI	1837	2018	24	Betsie-Platte; Black-Presque Isle; Boardman-Charlevoix; Clinton; Great Lakes Region; Huron; Keweenaw Peninsula; Lake Michigan; Lake St. Clair; Manistee; Northeastern Lake Michigan; Northwestern Lake Huron; Ontonagon; Pere Marquette-White; Raisin; Southcentral Lake Superior; Southeastern Lake Michigan; Southwestern Lake Huron-Lake Huron; St. Clair; St. Clair-Detroit; St. Joseph; Tittabawassee; Upper Grand; Western Lake Erie
MN	1937	2018	4	Baptism-Brule; Beaver-Lester; Lake Superior; St. Louis
NY	2008	2008	12	Cattaraugus; Great Lakes Region; Indian; Northeastern Lake Ontario; Oak Orchard-Twelvemile; Oneida; Oswego; Saranac River; Seneca; Southwestern Lake Ontario; St. Lawrence; Upper Genesee
OH	2008	2008	8	Black-Rocky; Cuyahoga; Huron-Vermilion; Lake Erie; Lower Maumee; Sandusky; Southern Lake Erie; Western Lake Erie
PA	2008	2008	1	Lake Erie
WI	1900	2018	11	Bad-Montreal; Lake Superior; Manitowoc-Sheboygan; Northwestern Lake Michigan; Oconto; Peshtigo; Pike-Root; Southwestern Lake Michigan; Southwestern Lake Superior; Upper Fox; Wolf

Table last updated 3/14/2025

† Populations may not be currently present.

Ecology: This species has been naturalized in relatively mesic, disturbed areas and sometimes in areas dominated by native species (Wagner et al., 1999). It is usually found near habitations, and is also common to abundant elsewhere in pastures, river banks and open moist places, and is a major weed of gardens and arable land. Plants are often very large and prolific around stockyards, cowsheds and other places with very high nitrogen levels. Found in disturbed, usually moist ground on floodplains, along roads and borders of forests, in clearings and fields (Reznicek et al. 2011).

It flowers from June to October, but flowering is delayed by early shoot removal. A large mature broad-leaved dock can produce up to 60,000 ripe seeds per year. The seeds become viable from the milk stage onwards, and immature seeds will continue to develop on stems cut down just a few days after flowering. Broad-leaved dock can shed seed from late summer through to winter but the seeds may require a short after-ripening period before being ready to germinate. Seedlings of broad-leaved dock generally do not flower in the first year.

Means of Introduction: Unknown.

Status: Established.

Great Lakes Impacts:

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental Socioeconomic Beneficial

Current research on the environmental impact of Rumex obtusifolius in the Great Lakes is inadequate to support proper assessment.
Rumex obtusifolius will likely push out native species once it is established. Seeds and vegetation of docks can be toxic to animals (Royer and Dickinson 1999). These plants can host a high diversity of plant pathogens and invertebrate pests that may affect surrounding plants (Dal Bello and Carranza 1995, Edwards and Taylor 1963, Townshend and Davidson 1962, Martinkova et al., 2009). Members of the genus Rumex are known to hybridize with each other (R. obtusifolius x R. crispus is known in the region), but the degree to which this might affect Great Lakes natives is unknown.

Current research on the socioeconomic impact of Rumex obtusifolius in the Great Lakes is inadequate to support proper assessment.
Docks are undesirable in grasslands because they decrease yields and reduce forage feeding value. As a weed of pastures and meadows, the main impact of this plant is to reduce the value of infested land as grazing for livestock. R. obtusifolius is only 65% as valuable as grass as grazing material because of a combination of reduced palatability (and therefore grazing levels) and reduced digestibility (Courtney & Johnson, 1978 in Grossrieder & Keary, 2004). It also contains oxalic acid, which may be poisonous to livestock in large quantities. Mature plants also suppress the grass yield of pasture. Oswald and Haggar (in Grossrieder & Keary, 2004) found that increasing ground cover by Rumex reduced grass yields, as did increasing Rumex density.

There is little or no evidence to support that Rumex obtusifolius has significant beneficial impacts in the Great Lakes.
Bitter dock is avoided by rabbits, but it appeared to be a favorite food plant of deer (Amphlett and Rea 1909, cited in Cavers and Harper 1964).

Management: Regulations (pertaining to the Great Lakes)
The Great Lakes Indian Fish & Wildlife Commission ranked R. obtusifolius as capable of low to moderate ecological impacts ,and does not consider it a priority for control within their ceded territories (Falcke and Garske 2003). There are no federal (or state within the Great Lakes region) regulations for this species.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control

Biological
Bitter dock is avoided by rabbits, but it appeared to be a favorite food plant of deer (Amphlett and Rea 1909, cited in Cavers and Harper 1964). Docks are grazed by cattle, sheep, and goats, but not by horses.

Cavers and Harper (1964) list a range of fungi and insects that attack, feed on or occur on docks but this not an indication that of their efficacy as control agents. The use of the stem boring larvae of the weevilsApion violaceum and A. miniatum for controlling Rumex obtusifolius has been investigated (Hopkins, 1980; Freese, 1995). In the UK and elsewhere, there has been research on the chrysomelid beetle (Gastrophysa viridula) as a biocontrol agent for both R. obtusifolius and R. crispus (Bentley et al., 1980). Larvae of the leaf-mining fly Pegomya nigritarsis cause blotch mines on leaves of R. obtusifolius (Whittaker 1994). Rumex obtusifolius is the preferred host plant of Coreus marginatus and has been shown to moderately reduce its seed viability (Hruskova et al 2005). The leaf spot fungus Ramularia rubella causes red spots to develop on dock leaves, but has no major effect on plant survival. The rust fungus Uromyces rumicis is also non-systemic but has been shown to have some potential as a biological control agent (Inman, 1971; Schubiger et al., 1986). Dock species are also an alternate host for number of viruses, funguses (Dal Bello and Carranza 1995), and nematodes (Edwards and Taylor 1963, Townshend and Davidson 1962).

Physical
Caution should be used in physical removal, as this plant can cause contact dermatitis.

Repeated cultivation is recommended for control of young (seedling) populations.

Mowing has little effect on established docks, but will prevent seed production. However, frequent cutting encourages taproot growth, branching shoots and may aid seedling development (from previous year’s seed bank) and so is not recommended. In a pasture heavily infested with docks the best option may be to plough and reseed with grass but not immediately. The docks are likely to regenerate both vegetatively and from seed, and a period of fallowing or arable cropping may help to reduce re-establishment.

Chemical
Many chemical controls are available for dock species. However, very few are approved for use in or near water. Repeated treatments are usually needed to control re-growth.

Dicamba (benzoic acid) is effective on curly dock (Rumex crispus) but not on broadleaf dock (R. obtusifolius). Picloram (pyridine) is effective on most Rumex species. 2,4-DB amine or 2,4-D ester are effective when applied beforethe flower stalk elongates, but require a 30 day withdrawl before feeding as forage. Aminopyralid can be applied to actively growing plants before the bud stage. Chlorsulfuron and metsulfuron can be used with young, actively growing plants, but should not be used on powdery, dry, or light sandy soils. Sulfoteturon has similar use, but should not be applied to cropland. Glyphosate can be used at early heading (Pacific Northwest Extension 2013).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

References (click for full reference list)

Other Resources:

Alaska Natural Heritage Program, Environment and Natural Resources Institute, University of Alaska Anchorage. http://akweeds.uaa.alaska.edu/pdfs/species_bios_pdfs/Species_bios_RUCR&RUOB.pdf

Organic Weed Management http://www.gardenorganic.org.uk/organicweeds/weed_information/weed.php?id=1

http://www.hear.org/Pier/species/rumex_obtusifolius.htm

USDA/NRCS PLANTS Database

Author: Berent, L., and R. Sturtevant

Contributing Agencies:

Revision Date: 8/15/2019

Citation for this information:
Berent, L., and R. Sturtevant, 2025, Rumex obtusifolius L.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?Species_ID=2663, Revision Date: 8/15/2019, Access Date: 3/15/2025

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.