Rumex obtusifolius, commonly known as bitter dock, broad-leaved dock, bluntleaf dock, dock leaf or butter dock, is a perennial weed in the family Polygonaceae. It is native to Europe but can now be found in the United States and many other countries around the world such as Australia and New Zealand.
Obtusifolius means 'obtuse-leaved' (obtuse + foliage).
Rumex obtusifolius is a perennial herbaceous flowering plant that grows to a height of 50 to 130 cm (20 to 51 in). It is easily recognizable by its very large oval leaves with cordate bases and rounded tips, some of the lower leaves having red stems. The edges of the leaves are slightly "crisped" or wavy, the upper surface is hairless and the under surface may be papillose. The leaves of this plant can grow to about 40 cm (16 in) in length. The stems are tough, often reddish, and unbranched until just below the inflorescence. The junctions of the petioles with the stems are covered by a sheath formed by two fused stipules known as an ocrea, a thin, paper-like membrane - a characteristic of the Polygonaceae family. The stem leaves are alternate and are narrowly ovate–lanceolate. The inflorescence consists of large clusters of racemes which contain small greenish flowers that change to red as they mature. The perianth-segments are in two whorls of three. Segments in the outer whorl are small and spreading while the inner whorl forms fruit valves, which are widely ovately-triangular. The seeds produced are dry and reddish brown. This plant blooms June through September.
Rumex crispus - curly dock - is very similar in appearance but with thinner and wavier 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. It is a plant of arable land, meadows, waste ground, roadsides, ditches and shorelines.
Seedlings can be identified by the oval leaves with red stems and rolled leaves sprouting from the center of the plant.
Leaves of the plant can be used as salad, to prepare a vegetable broth or to be cooked like spinach. They contain oxalic acid which can be hazardous if consumed in large quantities. Dried seeds are used as a spice. In Romania, 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.
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.
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- "Broad-leaved dock". Queensland Government. Retrieved 17 March 2016.
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- Ohio Perennial and Biennial Weed Guide
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- "List of Invasive species in the Great Lakes Great Lakes United / Union Saint-Laurent Grands Lacs". Archived from the original on 2009-04-29. Retrieved 2009-02-07.