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Re: family tree

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  • Steve Henning
    Although this article is named Genetic relationships within Rhododendron L. section Pentanthera G. Don , I find it interesting that several of the splits are
    Message 1 of 2 , Nov 23, 2012
      Although this article is named "Genetic relationships within Rhododendron L. section Pentanthera G. Don", I find it interesting that several of the splits are based upon morphological differences. Hence, the type of DNA study done here integrates DNA studies with classic morphology to make groupings and distinctions. Here are 2 examples:

      "Morphology supports the grouping of R. luteum and R. occidentale which share the characters of glandular bud-scale margins, an orange to yellow blotch on the upper corolla lobe, and glandular foliage."

      "R. austrinum morphologically resembles R. canescens but is distinguishable from R. canescens by the consistently glandular nature of its bud-scale margins, pedicels, petioles and leaf margins."

      They point out two of the problems with only using morphological data that are avoided with DNA studies:

      "Morphological characters have traditionally been used to distinguish species. Many characters are easily influenced by environmental factors or subject to human interpretation."

      "Variability within species and an absence of distinguishing morphological characteristics between species has caused difficulty in assembling the different taxa into well-defined groups."

      Steve Henning, Zone 6, Reading, PA USA

      --- In azaleas@yahoogroups.com, Larry Wallace <UUallace@...> wrote:
      >
      > family tree on p. 132
      >
      > http://elmu.umm.ac.id/file.php/1/jurnal/S/Scientia%20Horticulturae/Vol85.Issue1-2.July2000/1473.pdf
      >
      > --
      >
      >
      > Larry Wallace
      > Cincinnati
      >
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