Scottish Rock Garden Club Forum
General Subjects => Travel / Places to Visit => Topic started by: Lewis Potter on August 08, 2015, 11:22:29 PM
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Myself and the family brought ourselves to Audley End House near Saffron Walden. They where all interested in the House. I was was more interested in a tree that was in its gardens. Its called the Howard Oak or more scientifically Quercus x audleyensis. A rare hybrid between Q. ilex and Q. petraea. It is thought to be the only one in the world.
Three features led me to believe this particular tree was the Howard Oak. The first being that it has two different types of bark on the trunk.
The second being that some leaves where very broad, while others where deeply lobed. The third being the leaves where arranged randomly on the stem (Most trees have opposite or alternate arrangement).
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I live not far from Audley End but I had never heard of the Howard Oak. Although you describe it as a hybrid your description makes it sound more like a chimera (along the lines of Laburnocytisus 'Adamii' https://en.wikipedia.org/wiki/%2BLaburnocytisus_%27Adamii%27 ).
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My word, Lewis - a unique English Oak indeed, " identified by Augustine Henry as a hybrid of Holm Oak and Sessile Oak"
It may be that is may be considered to be coming to the end of its life which seems a great shame - and that propagation attempts seem not to be successful in the long term.*
* = http://www.monumentaltrees.com/en/gbr/england/essex/7609_audleyendhouse/ (http://www.monumentaltrees.com/en/gbr/england/essex/7609_audleyendhouse/)
It looks well enough in your photos - hope it stays around for another few hundred years!
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The tree is certainly not a graft, so not a hybrid as such, Grafting, apart from being very difficult, You need to graft onto a root stock of the same tree. (Think Japanese Maples at garden centres). Difficult as the tree produces flowers and pollen, but dud acorns.
Here is how it works taxonomically.
A graft chimarea, like +Laburnocytisus 'Adamii' is not a hybrid but a mix of different cells from two species. Laburnum and Chamaecytisus in this example. This is represented by the plus sign at the beginning of its latin name.
The common hybrid is between the same species or cultivars and is represented by a multiplication sign between the Genus and species name, so in the case of the Howard Oak, it would be Quercus x audleyensis
The last hybrid is between two plants of different genera, an inter-generic hybrid, and is represented by a multiplication sign and the beginning of the Latin name. So a common hedging plant, that grows very quick, is xCupressocyparis laylandii, a cross of the Monterey cypress, Cupressus macrocarpa and the Nootka cypress, Hesperocyparis nootkatensis
I sure you know that already Alan, But for those how don't, There is is. Yes its a shame no one has found a successful way of propagating it, and that its coming to the end of its like
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Lewis, I just thought your description, with different parts of the tree showing different characteristics, was more indicative of a chimera than a hybrid. A graft chimera is formed when a deliberate graft goes wrong in a very unusual way. But the accidental fusion of two plants could also cause the formation of a chimera; it does not have to be done deliberately. I agree that is not very likely but is it less likely than a true hybrid of which there is only one example in the world?