horizontal secondary branching

Discussion in 'Plants: Science and Cultivation' started by Boley, Dec 7, 2015.

  1. Boley

    Boley New Member

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    I've noticed that branches stemming from the trunk of a tree are capable of doing so at all 360 degrees about the axis of the trunk. However, branches stemming from the trunk's primary branches, or from any branch that is already horizontal, seem to have a strong tendency to do so horizontally - forming sort of a plane along their parent branch's axis. This is especially noticeable in some conifers like the eastern hemlock or white pine.

    I would like to understand what causes this to happen. Does a branch's phyllotaxis change based on its orientation or is the cause more external? Can anyone explain?
     
  2. vitog

    vitog Well-Known Member

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    It's likely to be genetically controlled and does not seem to apply to temperate fruit trees. I'm constantly pruning off vertical secondary branches that will become water sprouts.
     
  3. Daniel Mosquin

    Daniel Mosquin Renowned Contributor UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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  4. Boley

    Boley New Member

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    Well its an interesting article but I don't see how apical control would cause this…maybe its in there and I'm missing it. I'm not talking about suppressed lateral branches drooping to the sides. I'm wondering why the very bases of lateral shoots, on horizontally growing branches, appear mostly on the sides, and rarely on the top or bottom.

    Like this:
     

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  5. wcutler

    wcutler Renowned Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    On hemlocks. As Vitog mentioned, that doesn't seem to be much of a rule for all trees. And even for conifers, this one I posted that might or might not be a Juniper seems to be doing a lot of top branching:
    http://forums.botanicalgarden.ubc.c..._lulukurd_cutler_20151208_123556c-jpg.137880/
     
  6. Boley

    Boley New Member

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    I'm aware that it is not a rule for all trees. It's not even a strict rule within the trees it does occur. I'm just wondering why it seems to be a strong tendency for certain trees. Its hard to find pictures but I've even seen it on deciduous decurrent trees.
     

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  7. Daniel Mosquin

    Daniel Mosquin Renowned Contributor UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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    Start reading from page 193 in this book for information about different hypotheses surrounding diageotropism.
     
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  8. wcutler

    wcutler Renowned Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    Wow. Not only did I learn a new word (diageotropic - growing at right angles to the line of gravity), but it seems clearly not related to a search for light, if it even happens underground with roots.
     
  9. Boley

    Boley New Member

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    Hehe, yea my first time hearing of diageotropism. That does look like an interesting read, unfortunately the pages you mentioned don't appear to be available for free so I may have to consider buying it. Thanks guys.
     
  10. Daniel Mosquin

    Daniel Mosquin Renowned Contributor UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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    Google Books search is always like that. The link only lasts a few times. Make note of the title and maybe do a separate search for the title and the word, and perhaps you'll get a link to the pages.
     
  11. M. D. Vaden

    M. D. Vaden Active Member 10 Years

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    Seems like part of it is genetic like someone mentioned. If a twig extends outward, and buds are genetically in certain places, isn't that where the next twigs or shoots must originate? And if each species varies, then branching varies.

    Seems a good light gathering development too. I was thinking of how some trees have alternate or opposite buds, twigs and leaves, and the leave seem to often space evenly to the sides and lay flat facing upward. Hormones are involved.
     
  12. Lysichiton

    Lysichiton Active Member

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    For the best exploration I know of the spatial geometry of plants, and other things, try 3 videos by my favourite math teacher - Vi Hart. Here's part 1 of "Doodling in Math Class":

    Be patient, all will become clear by the time you get to part 3.
     

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