A unique oak: Nepal field trip part 3

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One of the plants that really intrigued me during my time in Nepal was a species of evergreen oak that is native to the Himalayas and nearby mountainous areas of Asia.  It goes by the name of Quercus semecarpifolia and, as far as I am aware, has no common English name.  Two things surprised me about this species.

First of all, it is heterophyllous, meaning that its leaves come in more than one type.  Leaves close to the ground are spiky and look a lot like those of holly (Ilex spp.) which is what I thought they were when I first saw them:

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Leaves higher up on the plant have far fewer, if any, spikes:

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One of the things I discussed with the students was the job of scientists to identify patterns and to develop hypotheses about processes, i.e. what had caused those patterns.  In this case, after some discussion, we decided that the heterophylly was probably an adaptation to defend the leaves against small browsing mammals such as deer (thanks to Narayan for this image):


The other thing that interested me about the oak was its overall growth form, which was tall (they grow to 30m) with rather short, stubby branches, very distinctive from a distance:

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The tree were especially striking in the evening mist:

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They look as though someone has been out with a chainsaw and trimmed them, but that’s not the case, they naturally grow that way.  The best hypothesis that we could come up with is that this is an adaptation that prevents the trees from accumulating large, heavy loads of snow which could result in branches breaking.

I’ve never seen this growth form, not heterophylly, in any other oak species, but Quercus is a large genus of about 600 species, so I wouldn’t be surprised if similar species exist.

Part 4 to follow.

5 thoughts on “A unique oak: Nepal field trip part 3

    1. jeffollerton Post author

      As far as we could tell, Mike, this is the natural growth form of the plants. Even on inaccessible slopes and ridges the trees looked like this.

      1. Clem

        Avoiding excessive snow loads does seem reasonable… and escape from extreme winds might also play a role. Both of these potential adaptation strategies could also be evident among other species in the area – did you notice any other species present with members from widely disparate environment(s)?

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