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Key to Convolvulus

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1 Leaves about as wide as long, rounded at the tip
1 Leaves longer than wide, obtuse , acute, or acuminate at the tip.
  2 Flowers double, the corolla deeply divided into many parts; [garden escape, occasionally naturalized]
  2 Flowers not double, corolla entire.
    3 Calyx not concealed by 2 large bracts (the bracts small and on the pedicel at a distance below the calyx); corollas < 3 cm long.
      4 Calyx 3-5 mm long; leaves sparsely pubescent; leaves entire and unlobed (except for the 2 basal lobes; corolla margins lacking sharp tips; [widespread in our area]
      4 Calyx 6-12 mm long; leaves sparsely to densely gray-pubescent; leaves entire, toothed, or deeply lobed (in addition to the 2 basal lobes; entire and unlobed (except for the 2 basal lobes; corolla margins lacking sharp tips; [se. KS, sw. AR, e. and s. TX westwards and southwards (and rarely a waif eastwards].
        5 Leaves deltoid in outline, thick, markedly veined, silvery-pubescent, and with dentate margins; seed coats smooth; [s. TX]
        5 Leaves variable in outline, thin, not markedly veined, thinly pubescent, and with margins dentate or not; seed coats papillose; [se. KS, sw. AR, e. and s. TX westwards and southwards (and rarely a waif eastwards].
          6 Sepals 6-8 mm long; corolla 1.4-1.8 (-2.3) cm long, usually pink
          6 Sepals 11-12 mm long; corolla 2.5-3 cm long, usually white but often with a dark centre
    3 Calyx concealed by 2 large bracts; corollas > 3 cm long.
             7 Leaves densely white-tomentose beneath
             7 Leaves pubescent or glabrous, but not densely white-tomentose beneath.
               8 Stems mostly less than 1.5 m, erect at least in the lower part, but sometimes twining toward the apex, flowers mostly borne in lower leaf axils.
                 9 Stems twining in the upper part; mostly 0.5-1.4 m high; leaves overtopping stem apex by < 1 cm.
                   10 Leaves whitish-pubescent; corolla 44-64 (-70) mm long; [east of the Mississippi River]
                   10 Leaves grayish-puberulent; corolla (35-) 40-52 (-69) mm long; [west of the Mississippi River]
                 9 Stems not twining, up to 0.6 m high; leaves overtopping the stem apex by 1.5-6 cm.
                     11 Stem and leaves tomentose; leaves tending to be folded along midrib at maturity
                     11 Stem and leaves glabrous to pubescent; leaves more or less flat at maturity
               8 Stems strongly twining, up to 4 m or more long; flowers borne along middle and upper stems.
                       12 Margins of the bracts immediately subtending the flower overlapping > ½ their length; bracts inflated at base (saccate), the apex usually obtuse; flowers 1-2 per axil
                       12 Margins of the bracts immediately subtending the flower overlapping at the base only or not at all; bracts mostly flat (or often keeled, the apex usually acute; flowers 1 per axil.
                          13 Bracteoles forming a continuous spiral series with sepals, the flower appearing to have 3 bracteoles when seen from side; leaves with almost closed sinus, the lobes posteriorly truncate
                          13 Bracteoles clearly distinct from sepals, obviously only 2; leaves with a wide or v-shaped sinus.
                            14 Corolla pink.
                              15 Leaves with basal lobes rounded or with a single angle, or if with 2 angles then not spreading; plant glabrous or commonly pubescent to tomentose on stem
                              15 Leaves with lobes with 2 angles, spreading; plant glabrous
                            14 Corolla white.
                                16 Corolla 48-70 mm long; stamens 25-32 mm long; leaf sinus acute or rounded (U-shaped); plant glabrous or pubescent.
                                  17 Leaves with posteriorly directed lobes, the blade often conspicuously narrowly triangular to linear; stems and leaves often strongly pubescent; [Coastal Plain]
                                  17 Leaves with spreading basal lobes, each lobe more or less 2-angled, sinus broadly rounded; plant glabrous; WV and northwards and westwards]