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Editor's Picks

Allan Taylor
A long-standing member of the IOS and fomer editor of Oak...
Panayoti Kelaidis | Dec 17, 2022
A new study resolves many nomenclatural problems in the...
Carlos Vila-Viçosa | Dec 09, 2022
The team at SDZWA
Christy Powell of the San Diego Zoo Wildlife Alliance works...
Amy Byrne | Dec 06, 2022

Plant Focus

Quercus macdougallii
A rare oak endemic to the Sierra Juárez in Oaxaca

Stretching the Rules

Quercus satillensis stretching out a limb with scant photosynthesizing surface at Arboretum de la Bergerette © Shaun Haddock
Quercus saltillensis © Shaun Haddock

An oak which breaks the rules... Do oaks have rules? Well, I think so: the rule of survival of the fittest implies that all unnecessary branch structure is unaffordably costly in resources – the aim of a tree should be to display the maximum leaf area for photosynthesis attached to the minimum possible structure. And the culprit in question? Quercus saltillensis, the two plants of which here at Arboretum de la Bergerette bizarrely throw out long branches with a minimal sprinkling of small leaves. It appears to do the same at Beatrice Chassé’s Arboretum de Pouyouleix, although it has to be said that our plants probably come from the same seed collection (Chassé G992). I have taken to broaching the subject with visitors, one of whom suggested the habit might exhaust and discourage predatory caterpillars…

Bees beguiled by catkins of Quercus muehlenbergii in Grigadale Arboretum, Argentina © Roderick Cameron

And more rule-breaking, this time by bees!

In mid-May 2017, in the blessed peace which ensued when my brushcutter ran out of fuel, there was an overwhelming buzz of bees. At the edge of a patch of woodland, there was not a flower in sight. Finally I looked up, and over my head the yellow catkins on a Q. suber were populated with bees, working steadily up and down the catkins. Now, everyone knows that oaks are wind-pollinated, so what was going on? Yes, I know that there is so-called “oak honey”, but this is made from the, ahem, by-products of aphids feeding on the leaves. So I checked out the few catkins which were in reach to see if they also were infested with aphids, but no. So, were the bees “stealing”  the pollen without providing any pollination function in return? Your thoughts please to shaun.haddock@orange.fr or as a comment below.

The answer to Shaun's question can be found in a subsequent post in his blog. You can view it here.