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Key to Lysimachia

Primulaceae

Lysimachia

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1 Leaves alternate (or with some opposite or subopposite); flowers white.
  2 Flowers axillary, nearly sessile or pedicellate; leaves 0.3-1.0 cm long.
  2 Flowers in a terminal raceme, pedicellate, the flowers closely spaced, touching, the inflorescence thus appearing cylindrical, and generally drooping at the tip (reminiscent of Saururus cernuus); leaves 4-16 cm long; [introduced, rarely naturalized in upland situations]
    3 Corolla lobes 5-8 mm long; leaf blades 4-10 cm long × 0.6-2.2 cm wide, epunctate
    3 Corolla lobes 3.5-4.5 mm long; leaf blades 6-16 cm long × 2-5 cm wide, sparsely punctate with black glands
1 Leaves opposite or whorled; flowers yellow, white, pink, red, or blue.
      4 Leaves in a single terminal whorl; petals 7; flowers white
      4 Leaves opposite or whorled (if whorled, with several to many whorls); petals 0 or 5; flowers yellow, red, blue, white, or pink.
        5 Leaves < 2 cm long (and distinctly longer than wide); flowers red, blue, white, or pink.
          6 Flowers nearly sessile; corolla absent
          6 Flowers on long pedicels; corolla present.
        5 Leaves > 2 cm long (sometimes less in L. nummularia, and then orbicular, and about as wide as long); flowers yellow
             7 Leaves nearly round; plant trailing, rooting at nodes
               8 Flowers 5-7 mm across; sepals about 1× as long as the petals; stem pilose
               8 Flowers 16-24 mm across; sepals about ½× as long as the petals; stem glabrous
             7 Leaves linear, lanceolate, elliptic, or ovate; plant erect (or trailing and rooting at the nodes in L. radicans, which has lanceolate leaves).
                 9 Flowers in a terminal raceme or panicle, subtended by bracts much smaller than the stem leaves.
                   10 Inflorescence a terminal panicle
                   10 Inflorescence a terminal raceme.
                     11 Leaves narrowly ovate, broadest near the base, with 3 prominent veins
                     11 Leaves linear to lanceolate, broadest near the middle, with 1 prominent vein.
                       12 Leaves linear to narrowly lanceolate, (1-) 2-4 (-8) mm wide; sepals stipitate-glandular
                       12 Leaves lanceolate to elliptic, 7-20 mm wide; sepals glabrous.
                          13 Flowers in part (the lower) in the axils of well-developed leaves
                          13 Flowers all in the axils of much reduced linear bracts
                 9 Flowers axillary, all or most of them subtended by leaves similar in shape to (though often somewhat smaller than) stem leaves not subtending flowers (or with flowers in axillary, peduncled, densely-flowered racemes in L. thyrsiflora).
                            14 Flowers in peduncled axillary racemes in the axils of midstem leaves; petals linear to lanceolate, ca. 5 mm long and ca. 1 mm wide, much surpassed by the stamens
                            14 Flowers solitary, all or most of them subtended by leaves similar in shape to (though often somewhat smaller than) normal stem leaves; petals lanceolate to ovate, as long or longer than the stamens.
                              15 Stem leaves opposite; leaves not “punctate” (as described below).
                              15 Stem leaves whorled (in adult plants – juvenile plants with opposite leaves or a mixture of opposite and whorled); leaves “punctate” with sinuous, elongate markings (visible with the naked eye, but more readily observed with 10 × magnification).
                                16 Petals yellow, marked with black lines; sepals 2.5-5 mm long; stem glabrous or sparsely pubescent; [native]
                                16 Petals plain yellow, not marked with black lines; sepals 2.5-4.5 mm (L. vulgaris) or 5.5-9 mm long (L. punctata]; stem hairy; [exotic].
                                  17 Calyx lobes 5-8 mm long, green throughout; corolla lobes 12-16 mm long, glandular-ciliolate
                                  17 Calyx lobes 3-5 mm long, with red margins; corolla lobes 8-12 mm long, entire