Rumex obtusifolius
Rumex arcticus
bitter dock, broad-leaf dock, broad-leaf or broadleaf or bitter dock, patience a feuilles obtuses
arctic dock
erect, branched distal to middle or occasionally in distal 2/3, often with few flowering stems from rootstock, 60–120(–150) cm.
erect, simple or branched in distal 2/3 (then with few, comparatively short branches), 10–70(–100) cm.
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.
ocrea deciduous or partially persistent at maturity;
blade narrowly lanceolate, lanceolate, or oblong-lanceolate, normally 5–15(–20) × 1.5–5 cm, base cuneate to broadly cuneate, rarely truncate or very weakly cordate, margins entire or rarely indistinctly repand, flat, apex acute or subacute.
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.
terminal, occupying distal 1/2–2/3 of stem, interrupted, paniculate, simple or nearly so (branches, when present usually less than 7–8 cm).
articulated in proximal 1/3 or rarely near middle, filiform, 2.5–8.5(–10) mm, articulation distinctly swollen.
articulated in proximal 1/3, filiform, 5–13(–17) mm, usually not more than 2–2.5 times as long as inner tepals, articulation weakly evident, not swollen.
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.
7–15 in whorls;
inner tepals ovate, 4.5–7.5(–8) × 4–6(–7) mm, base truncate to weakly cordate, margins entire, apex obtuse or subacute;
tubercles absent.
brown to reddish brown, 2–2.7 × 1.2–1.7 mm.
reddish brown, 3–4 × 1.5–2 mm.
= 40.
= 40, 120, ca. 170, ca. 200.
Rumex obtusifolius
Rumex arcticus
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Rumex arcticus is polymorphic, as are R. aquaticus in the narrow sense and R. occidentalis. However, unlike R. aquaticus and R. occidentalus, it is represented by at least two chromosome races (G. A. Mulligan and C. Frankton 1972; Á. Löve 1986). Plants morphologically transitional between R. arcticus and R. aquaticus were described from Kamchatka as R. kamtschadalus (= R. arcticus var. kamtschadalus). The same forms occasionally occur in northwestern North America. According to Á. Löve and D. Löve (1975b) and Á. Löve (1986), they are usually tetraploids (2n = 40) and deserve recognition at the species level. However, they are not always morphologically distinct from R. arcticus. The group needs additional study, and at present I prefer to keep the tetraploid plants provisionally within R. arcticus, regarding them as var. kamtschadalus.
A few highly sterile specimens with mostly abortive flowers, which I have seen in Alaskan herbarium material, most probably represent hybrids between tetraploid and 12-ploid races of the R. aquaticus group.
Plants with unusually wide, triangular-oblong, or almost ovate leaves were described as var. latifolius Tolmatchew. This seems to be a predominant variety on the Beringian coast of Chukotka and Wrangel and Ratmanov islands (A. I. Tolmachew 1966). I also have seen at least two collections of this variety from the western coast of Alaska. The enigmatic var. perlatus Hultén may belong here (see discussion under 8. R. lapponicus).
Rumex arcticus has been reported from Churchill in northeastern Manitoba (H. J. Scoggan 1978–1979, part 3). That record needs confirmation because some northern forms of R. arcticus and R. occidentalis are similar.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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