Thursday, 11 October 2018

Oaks around Byfield

We have two native oaks in Britain, Quercus robur and Q. petraea, plus two species which are well naturalised - too well naturalised in some areas. The common oak of lowland Britain is the Pedunculate oak, Q. robur, and there are several specimens around Byfield. The acorns in their cups are on the end of a stalk - the peduncle - an inch or so long. The leaves have rounded lobes at the base.

A leaf of Quercus robur, showing lobes at the base. Byfield, Northants.
10 October, 2018

There are specimens of Q. petraea within a few miles of Byfield but I have not found one within the village.

Easily mistaken for either of these common oaks is the Turkey Oak, Q. cerris, of which two specimens stand beside the village hall car park. It is one of our two naturalised species.  I will not weary any readers with details of the Turkey Oak's features as I have written of this species before. Just a reminder that the leaf tends to have a greater number of lobes and these are slightly pointed. The acorn cup is covered in rather long curvy scales, looking like whiskers.
The leaf lobes of Q. cerris come almost to a point. Byfield.
10 October, 2018

Three examples of the Holm Oak, Quercus ilex, otherwise simply known as the Ilex, stand in the village pocket park. Actually I should say stood, for in the last few days two of them have been unaccountably felled.
Many oaks have evergreen leaves but Q. ilex is the only species commonly found in the U.K.
Byfield Pocket Park. 10 October, 2018

The glossy leaves look, to our eyes, very un-oak-like, but interestingly leaves produced on young stems at the base of the tree are prickly and rather like holly. It is worth remembering that the Latin name for holly is Ilex aquifolium. The Holm Oak does produce small acorns but not reliably and I have been unable to find any this year.

The Holm Oak is native to countries around the Mediterranean and is the second of our naturalised species, but we have a North American species in Byfield too. For some time I have been unsure about its identity but this year I found a number of its odd little acorns scattered beneath the tree.

They are curious flat structures and enabled me to determine that it is Quercus palustris. The Americans call it a Sallow (we use the word sallow for a species of willow). It is also known as Pin Oak.

Leaf and cones of Q. palustris. Byfield, 10 October, 2018
The acorns seem not always to develop properly and the specimens I found were certainly oddly flattened, but they do match the structures described in some of my books. It may be that the species is self-sterile and for proper acorn development needs to be pollinated from another specimen.

The acorns seem to be under-developed.
On thing is sure: the tree takes on lovely autumnal colours and certainly justifies a place in Byfield, where it stands adjacent to the tennis courts.

The Byfield specimen of Quercus palustris is currently a fine sight. 10 October, 2018
In having only two species native to Britain we have missed out, for oak trees, in their various forms consist of between 300 and 600 species depending on the criteria employed by the individual taxonomist, but 450 would seem a reasonable figure. I have frequently found leaves of North American oaks in country lanes with the parent tree(s) not apparent. Autumn leaves clearly get carried over considerable distances.

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