Rumex mexicanus
Rumex arcticus
Mexican dock, Mexican willow, Mexican willow or dock
arctic dock
erect or ascending, usually producing axillary shoots below 1st-order inflorescence or at proximal nodes, 30–60(–90) cm.
erect, simple or branched in distal 2/3 (then with few, comparatively short branches), 10–70(–100) cm.
blades light green to yellowish green, linear-lanceolate, occasionally lanceolate, 6–14 × 1–3.5(–4) cm, usually ca. 5–7 times as long as wide, widest near middle, thin, not coriaceous, base cuneate, margins entire, flat or undulate, apex acute or attenuate.
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 and axillary, terminal usually occupying distal 1/5–1/3 of stem, rather dense or interrupted in proximal 1/2, usually broadly paniculate (branches simple or with few 2d-order branches).
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 almost near base, filiform (thickened distally), 4–7 mm, not more than 2–2.5 times as long as inner tepals, articulation indistinctly 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.
10–20 in whorls;
inner tepals broadly ovate-triangular, occasionally broadly triangular, 3.5–4.5(–5) × 3.5–4(–5) mm, base truncate or indistinctly cordate, margins entire or indistinctly erose, apex obtuse or subacute;
tubercles 3, equal or subequal (much narrower than inner tepals).
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 or dark reddish brown, 2–3 × 1.5–2 mm.
reddish brown, 3–4 × 1.5–2 mm.
= 40.
= 40, 120, ca. 170, ca. 200.
Rumex mexicanus
Rumex arcticus
Some authors recognize Rumex mexicanus in the broad sense, including in it many other taxa treated here as separate entities. For consistency, the entities of the R. salicifolius aggregate that are recognized herein are kept separate pending additional taxonomic research.
(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.)
OR
Flora NW
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
