Rumex mexicanus
Rumex persicarioides
Mexican dock, Mexican willow, Mexican willow or dock
American golden dock, golden dock, rumex fausse-persicaire, seashore dock, yellow dock
erect or ascending, usually producing axillary shoots below 1st-order inflorescence or at proximal nodes, 30–60(–90) cm.
erect, branched in distal 2/3, occasionally almost near base, especially in dwarf littoral plants, (5–)15–70(–90) 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 to partially persistent at maturity;
blade lanceolate or oblong-lanceolate, 5–25(–30) × 1.5–5 cm, at least 4 times as long as wide, base abruptly truncate, slightly cordate or, rarely, broadly cuneate, margins entire, weakly undulate or crisped, apex acute or occasionally subobtuse.
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 of stem (occasionally most of stem), usually dense in distal part, interrupted in proximal part, broadly paniculate.
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 near base or at least in proximal 1/3, filiform, 3–7 mm, articulation weakly evident.
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).
15–25 (occasionally more) in rather dense whorls;
inner tepals narrowly triangular or narrowly rhombic-triangular, 2–2.5 × 0.75–1(–1.5) mm (excluding teeth), normally ca. 2 times as long as wide, base truncate or broadly cuneate, margins prominently dentate, apex acute, very rarely subacute, straight, teeth 2–3, normally at each side of margins, subulate-filiform, bristlelike, straight, 1–1.5(–1.7) mm, usually as long as width of inner tepals;
tubercles 3, straw colored, oblong-ovate, ± equal, ca. as wide as inner tepals excluding teeth, apex obtuse, normally reticulate-pitted.
brown or dark reddish brown, 2–3 × 1.5–2 mm.
brown, 0.9–1.5 × 0.5–0.8(–1) mm.
= 40.
= 40.
Rumex mexicanus
Rumex persicarioides
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 persicarioides often has been treated by American botanists as a variety or synonym of R. maritimus (see R. S. Mitchell 1978). It and R. fueginus differ from Eurasian R. maritimus in many respects and are as distinct as many widely recognized Eurasian taxa of this aggregate (e.g., R. palustris, R. rossicus Murbeck, R. ucranicus Fischer ex Sprengel, R. marschallianus Reichenbach, R. amurensis Fr. Schmidt ex Maximowicz, R. evenkiensis Elisarjeva). When submerging R. persicarioides as a variety of R. maritimus, Mitchell noted: “Taxonomic treatment of the group from a Eurasian point of view would undoubtedly shed light on the minor problems which we face in North and South America.” However, from a Eurasian point of view (see e.g., K. H. Rechinger 1937, 1949; J. E. Lousley and D. H. Kent 1981; N. N. Tzvelev 1989b), all North American native taxa of subsect. Maritimi are evidently specifically different from any native Eurasian ones (with the only possible exception of Pacific plants, which are discussed below).
Plants similar to Rumex persicarioides, but with bigger tubercles and occuring along the Pacific coast from northern California to British Columbia, are, in my opinion, closer to R. fueginus in their habit and vegetative characters. K. H. Rechinger (1937) provisionally determined such specimens as R. persicarioides. J. E. Dawson (1979) noted that the Pacific plants differ from Atlantic ones in having bigger tubercles (more than 1.9 × 0.7–1 mm in western plants; less than 1.9 × 0.7 mm in eastern R. persicarioides in the narrow sense), and described these large-tubercled plants as a distinct variety, “R. maritimus var. pacificus, unfortunately, an invalid name. However, that taxon seems to be extremely closely related to or possibly conspecific with the northeastern Asian species, R. ochotskius Rechinger f., which is known in eastern Asia from northern Japan to the Okhotsk Sea region of Russian Far East (especially Sakhalin and Kuril islands). The latter species also has large (to 2–2.5 mm) botuliform tubercles with obtuse apices. In the original description Rechinger stated: “…foliorum forma R. maritimo simillimus…,” but N. N. Tzvelev (1989b) in his recent treatment of the genus in the Russian Far East noted that most of the specimens of R. ochotskius seen by him had leaf blades rotundate-truncate or broadly cuneate at the base. The R. persicarioides-like plants from the Pacific coast of the United States and Canada (as well as their most probable allies from eastern Asia) need additional study. At present I prefer to place them provisionally into R. persicarioides, following Rechinger’s treatment.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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