Rumex obtusifolius, commonly known as bitter dock, broad-leaved dock, bluntleaf dock, dock leaf, dockens or butter dock, is a perennial plant in the family Polygonaceae. It is native to Europe, but is found on all temperate continents. It is a highly invasive species in some zones, resulting from its abundant seed dispersal, adaptability to reproduce, aggressive roots, ability to tolerate extreme climates, and hardiness. while obtusifolius means 'obtuse-leaved' (obtuse + foliage).

Rumex crispus – curly dock – is similar in appearance, but with thinner and wave-like leaves. In more detail, the calyx of curly dock has smooth margins while the calyx of broad-leaved dock has horned margins.

Distribution and habitat

Rumex obtusifolius is widely distributed throughout the world. The dried seeds can be ground to make flour. In Turkey, Romania and Greece the leaves are sometimes used as an alternative to other plants in the making of sarmale. A tea prepared from the root was thought to cure boils.

In Ireland and the United Kingdom, the plant is often found growing near stinging nettles and there is a widely held belief that the underside of the dock leaf, squeezed to extract a little juice, can be rubbed on the skin to counteract the itching caused by brushing against a nettle plant. This home remedy is not supported by any science, although it is possible that the act of rubbing may act as a distracting counterstimulation, or that belief in the dock's effect may provide a placebo effect.

History

In George Eliot's Adam Bede, set in the early 19th century, broad dock leaves were used to wrap farmhouse butter.

Host plant

Rumex obtusifolius is a major host plant for many different insects as well, including the Acronicta rumicis moth. For A. rumicis research, this host plant is generally targeted because it is found highly within the moth's range.

Invasiveness and eradication

Rumex obtusifolius is an aggressive invasive species on all temperate continents.

Various parasites and predators of R. obtusifolius include 32 insect species and 12 fungi species.