The preference is full or partial sun, moist to mesic conditions, and a loamy fertile soil. This robust plant will grow readily in less favorable situations, but it will be smaller in size. It can tolerate temporary flooding and is more often in partially shaded situations than many other Rumex spp. (Docks). The seeds of Docks can persist in the ground for several decades and remain viable.
Anhui, Gansu, Hebei, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Taiwan, Zhejiang [Japan, Russia; N Africa, Europe; introduced and naturalized in North America and other regions of the world].
Rumex obtusifolius, commonly known as broad-leaved dock, bitter dock, bluntleaf dock, dock leaf or butter dock, is a perennialweed 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.
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 broadleaf dock has horned margins.
Broadleaf dock is considered a weed and is slightly poisonous. It is designated an "injurious weed" under the UK Weeds Act 1959. Livestock have been known to get sick after feeding on it. But eradicating the plants is difficult. The perennial plant can have a deep taproot reaching 5 feet down. Also, the milk of the plant has been known to cause mild dermatitis.
Seeds have toothed wing structures, allowing them to be dispersed by wind or water, and also allow them to attach to animals or machinery to be spread great distances. They can lie dormant for years before germination, making vigilant pulling or tilling essential.
First year plants can seed, making early detection important for eradication.
The main weaknesses of Broadleaf are its poor competition, crowding causes flowering to be delayed for up to three years, and its susceptibility to disturbance. Frequent tilling will disrupt the roots and kill the older plants and seedlings. The plant also thrives in moist environments and improved drainage can also help control its growth.
It has also been an invasive species of the Great lakes region of North America where it was first sighted in 1840.
Rumex obtusifolius, a member of subsect. Obtusifolii Rechinger f. (K. H. Rechinger 1937), is a polymorphic species represented in Eurasia by three or four rather distinct races often treated by European authors as subspecies or varieties. These taxa differ mostly in inner tepal dentation and geographic distribution. In North America the morphotypes often intergrade. In Eurasia this species is differentiated into predominantly western subsp. obtusifolius [including R. obtusifolius subsp. agrestis (Fries) Danser], eastern subsp. sylvestris (Wallroth) Rechinger f., intermediate central European subsp. transiens (Simonkai) Rechinger f., and montane subsp. subalpinus (Schur) Simonkai. Only subspp. obtusifolius and sylvestris occur in North America; the former seems to be more common. Subspecies obtusifolius differs from subsp. sylvestris in having larger and more prominently dentate inner tepals with one tubercle, or with three distinctly unequal tubercles; in subsp. sylvestris the teeth are usually less than 0.6 mm, developing only near the base of the inner tepals, and the tubercles often almost subequal.
Rumex obtusifolius may be expected elsewhere in the Great Plains region of the United States and Canada.
Plants perennial, 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: ocrea deciduous to partially persistent at maturity; blade 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 terminal, occupying distal 2/ 3 of stem, usually lax and interrupted, narrowly or broadly paniculate, branches usually forming angle of 30-45° with 1st-order stem. Pedicels articulated in proximal 1/3 or rarely near middle, filiform, 2.5-8.5(-10) mm, articulation distinctly swollen. Flowers 10-25 in lax whorls; inner tepals 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 brown to reddish brown, 2-2.7 × 1.2-1.7 mm. 2n = 40.
Herbs perennial. Roots vertical, large, to 1.5 cm in diam. Stems erect, 60-120(-150) cm tall, grooved, branched above middle or in upper 2/3, glabrous. Basal leaves: petiole 6-12 cm, minutely papillate; leaf blade broadly ovate to oblong-ovate or narrowly ovate, 15-30 × 6-15 cm, base cordate, abaxially sparsely minutely papillate, adaxially glabrous; cauline leaves shortly petiolate, narrowly ovate, small; ocrea fugacious, membranous. Inflorescence broadly paniculate, large; branches ascending. Flowers bisexual, dense. Pedicel filiform, slender, articulate below middle (in proximal third, rarely near middle). Inner tepals enlarged in fruit; valves narrowly triangular-ovate, 4-6 × 2-3 mm, usually 1 valve with tubercles, sometimes 3 valves with tubercles, but then 1 tubercle distinctly larger than other 2, base truncate, each margin with 2 or 5 teeth, apex obtuse to subacute; teeth 0.8-1.5 mm, apex straight. Achenes dark brown, shiny, ovoid, sharply trigonous, ca. 2.5 mm. Fl. May-Jun, fr. Jun-Jul. 2n = 40.