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Rumex obtusifolius, broad-leaved dock

Summary

'Touch a nettle, get a dock' may be the best known piece of plant folklore but there is no evidence of anything other than a placebo effect.

Family

Polygonaceae

Meaning of the Name

Rumex
The circular definition, Latin for ‘sorrel’ seems to be the only one available.
 
obtusifolius
Latin ‘obtusi’, ‘blunt’ and ‘folium’, ‘leaf’ for the shape.

Common Names and Synonyms

broad-leaved dock, bitter dock.

How Poisonous, How Harmful?

The toxic component is calcium oxalates. These needle-shaped crystals can irritate the skin, mouth, tongue, and throat, resulting in throat swelling, breathing difficulties, burning pain, and stomach upset.

Oxalates in plants preferentially bind to calcium in the body. Regular ingestion in small amounts can lead to calcium deficiency and to the build up of kidney stones if the calcium oxalate formed is not excreted.

Its unattractive appearance combines with, as suggested by its alternative common name, its unpleasant taste to mean it is not a plant that is regularly consumed. 


Rumex obtusifolius, broad-leaved dock

Rumex obtusifolius, broad-leaved dock

Incidents

No reported incidents in humans but this and other species of Rumex have been associated with poisoning in sheep and cattle.

Folklore and Facts

Best known as the alleged antidote to nettle sting though there is no proof of its efficacy. It has been suggested that the dock is alkaline and counteracts the acidity of the nettle there is not even agreement that it is acidity in nettles which cause the sting.

'Touch a nettle, get a dock', however, is one of those beliefs where very few people occupy the centre ground. Most people either believe dock works in seconds or that it is of absolutely no value.

Dock provides another example of the misunderstandings behind many of the stories told by visitors to the Alnwick Garden Poison Garden. A visitor said that Native Americans smoke the leaves of Rumex and it is known as ‘Indian Tobacco’. According to the literature, Lobelia inflata is ‘Indian Tobacco’. This plant does look a bit like dock so that may be how the confusion arises.

Rumex obtusifolius is one of the five injurious weeds named in the 1959 Weeds Act and is very frequently seen in pasture land. One of the others is Jacobaea vulgaris (syn. Senecio jacobaea), common ragwort, but the broad-leaved dock does not attract the same hysteria as is created by the ragwort.