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Key to Rumex

Polygonaceae

Rumex

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1 Leaf blades of well-developed leaves (at least) hastate or sagittate; plants dioecious (rarely polygamo-monoecious), the flowers mostly unisexual; fresh foliage pleasantly acid to taste.
1 Leaf blades not hastate or sagittate; plants synoecious (rarely with some dioecious or polygamo-monoecious individuals), the flowers normally bisexual (sometimes bisexual and unisexual flowers in the same inflorescence); fresh foliage “green” or bitter to taste.
  2 Leaves primarily cauline; inner tepal margins entire (or nearly so); [subgenus Rumex; section Axillares].
    3 Inner tepals 23-30 mm wide, at least 20 mm in width, distinctly double-reticulately veined
    3 Inner tepals not (or rarely) exceeding 15 mm in width, singly-reticulately veined (or obscurely veined, if at all).
      4 Pedicels 2.5-5× as long as the inner tepals; pedicel joint (articulation) below the midpoint of the pedicel.
        5 Leaf blades ca. 2× as long as wide; lateral veins of leaves forming angle of ca. 80° to midvein
        5 Leaf blades 3-7 (-10)× as long as wide; lateral veins of leaves forming angle of 40-60° to midvein.
          6 Leaf blades 3-5 (-6)× as long as wide; coriaceous and usually somewhat fleshy; inflorescences dense (interrupted only at base); pedicels 2.5-3× as long as the inner tepals; inner tepals as wide as or wider than long
          6 Leaf blades 5-7 (-10)× as long as wide; thin; inflorescences interrupted in at least the lower half; pedicels 3-5× as long as the inner tepals; inner tepals longer than wide (rarely as long as wide)
      4 Pedicels usually < 2.5× as long as the inner tepals (or shorter than); pedicel joint (articulation) either at the midpoint of the pedicel, or below it.
             7 Leaf blades widest toward the apex; leaf apex rounded or obtuse
             7 Leaf blades widest at the middle or toward the base; leaf apex acute or attenuate (rarely nearly obtuse).
               8 Leaf blades widest toward the base (proximal 1/3); inner tepals 4.5-6 x 3-4.5 (-6) mm (R. altissimus) or 7-10 x 8-12 mm (R. spiralis)
                 9 Base of inner tepals (proximal-most portion) truncate or indistinctly cordate; inner tepals 4.5-6 mm long; plants with vertical rootstock; [widespread in US in a variety of wet habitats]
                 9 Base of inner tepals (proximal-most portion) deeply and broadly cordate; inner tepals 7-10 mm long; plants with creeping rhizomes; [sandy and gravelly shores, TX]
               8 Leaf blades widest near the middle; inner tepals (2-) 2.5-4.5 (-5) mm long, (2-) 2.5-4 (-4.5) mm wide.
                   10 Inflorescence lax, distinctly interrupted; leaf blades thick and coriaceous, deep green, with veins prominent on the lower surface; leaf apex nearly obtuse; inner sepals 3.5-4.5 (-5) mm long, 3-4 (-4.5) mm wide
                   10 Inflorescence dense, interrupted only toward its base; leaf blades light or yellowish green, the veins on the lower surface not noticeably prominent; leaf apex acute; inner sepals (2-) 2.5-3.5 (-3.8) mm long, (2-) 2.5-3 (-3.5) mm wide
  2 Leaves basally disposed, the largest and best developed in a basal rosette (these sometimes withering at maturity, especially in annual species); inner tepal margins entire or variously dentate; [subgenus Rumex; section Rumex].
                     11 Inner tepal margins entire, indistinctly erose, or (rarely) minutely denticulate (the teeth then < 0.2 mm long).
                       12 Inner tepals ca. 2× as long as wide, margins entire, largest tubercle almost as wide as the inner tepal.
                          13 Tubercles 3, equal or nearly so in size; inflorescence leafy through at least 2/3 of its length; pedicels 1.4 (-5) mm long
                          13 Tubercles 1 (or if 3, then one much larger than the other 2); inflorescence leafy only in basal 1/3 or less of its length; pedicels (2-) 4-6 (-8) mm long
                       12 Inner tepals ca. 1-1.5× as long as wide, margins entire or denticulate, largest tubercle much narrower than the inner tepal (or tubercle absent in R. hymenosepalus).
                            14 Tubercles 3, equal or nearly so in size; leaf blade >8× as long as wide, 20-55 (-70) cm long, 2-7 cm wide
                            14 Tubercles absent, 1 or 2-3 (if 2-3, then one much larger than the other 1 or 2 tubercles); leaf blade <6× as long as wide, 15-45 (-50) cm long, 2-15 cm wide.
                              15 Plants with distinctly tuberous roots and short lateral rhizomes; leaves whitish or silvery-white; [native, deep sands, e. TX westward; subsection Hymenosepali]
                              15 Plants with fusiform, vertical rootstocks; leaves green; [non-native, widespread in disturbed habitats of e. and w. US]
                                16 Leaf blade 15-30 (-35) cm long, 2-6 cm wide, the margins strongly undulate; inner tepals 3.5-6 mm long; tubercles normally 3 (rarely 1-2)
                                16 Leaf blade 30-45 (-50) cm long, 10-15 cm wide; the margins plane or weakly undulate; inner tepals (5-) 5.5-8 (-10) mm long; tubercles normally 1 (rarely 2-3)
                     11 Inner tepal margins prominently dentate, at least some of the teeth > 0.3 mm long.
                                  17 Inner tepals (not including the teeth) orbiculate-ovate to deltate, as wide as long
                                  17 Inner tepals (not including the teeth) ovate-triangular, triangular, or narrowly-triangular, evidently longer than wide.
                                    18 Inner tepals with 3-5 strongly hooked teeth on each side
                                    18 Inner tepals with straight teeth.
                                       19 Leaf blade > 4× as long as wide; inner tepals (not including the teeth) ca. 2× as long as wide
                                         20 Bases of leaf blades narrowly cuneate (rarely broadly cuneate); abaxial surface of leaf blades and inflorescence branches glabrous or inconspicuously papillose; tubercle of the inner tepals usually smooth; [non-native of disturbed habitats, NJ northward]
                                         20 Bases of leaf blades abruptly truncate to slightly cordate (occasionally broadly cuneate); abaxial surface of leaf blades and inflorescence branches papillose-pubescent; tubercle of the inner tepals distinctly reticulate-pitted; [natives in a variety of coastal and inland wetland and riparian habitats, collectively widespread]
                                           21 Tubercles linear-lanceolate to fusiform with acute to subacute apices, ½ the width of the inner tepals (excluding the marginal teeth), brown to red-brown (on fresh plants); teeth of inner tepal margins 1.5-2.5x as long as inner tepal width; [scattered throughout our area]
                                           21 Tubercles oblong-ovate with obtuse apices, similar in width to inner tepals (excluding the marginal teeth), cream to white-yellow (on fresh plants); teeth of inner tepal margins ± equal to inner tepal width; [rare, saline-influenced coastal wetlands, Long Island (historical) northward]
                                       19 Leaf blade 2-3× as long as wide; inner tepals (not including the teeth) ca. 1.5× as long as wide (sometimes to 2× as long as wide in R. obtusifolius).
                                             22 Plants perennial; base of leaf blade usually distinctly cordate.
                                               23 Stems 6-12 (-15) dm tall; leaf blades 20-40 cm long; inflorescence branches normally ascending, making an angle of 30-45° with inflorescence axis; tubercles of the inner tepals smooth
                                               23 Stems 2-6 (-7) dm tall; leaf blades 4-10 (-15) cm long; inflorescence branches spreading, making an angle of 60-90° with inflorescence axis; tubercles of the inner tepals usually verrucose
                                             22 Plants annual or biennial; base of leaf blade cuneate (rarely rounded).
                                                 24 Inner tepals 4-5 (-5.5) mm long; tubercles of the inner tepals verrucose
                                                 24 Inner tepals 3-4 mm long; tubercles of the inner tepals smooth or minutely punctate