From Mighty Oaks?

Oak leaf To my shame, I’m not a plant scientist, which means I might be about to ask a silly question. But maybe not, so here goes.


Every year at this time I collect oak (Quercus robur) leaves. We don’t need to go into the reasons why (I need the tannins), but it’s something I look forward to. I love the smell of oak leaves, and for me it marks the turning of the season. Mists and mellow fruitfulness? Give me a thick carpet of oak leaves and hazy sunlight every time.

After the rain we had overnight, I popped out this afternoon when the sun came out and made my first collecting foray of this year. And I noticed something strange. I have favourite trees I collect from each year because they are convenient and because they a located where the leaves tend to be clean and carry little pollution. The leaves I have collected from these old friends today are the largest I have ever seen. I don’t have any formal data, but in 10 years of doing this, I have never seen leaves of this average size.

My working hypothesis is that the high rainfall during this year’s growing season is the reason for the large leaf area. Alternatively, I suppose it could be possible that low light levels during the early part of the growing season might have played a part?

So my question to you, O noble plant scientist, is – what’s going on here? And is there any data in the literature which supports either of these ideas, either in oaks or other species?



  1. Environmental effects, e.g. temperature, rainfall, absolutely play a role in the expression of tree morphological characteristics. Often the effect correlates with conditions during the last growing year but in some species effects can even be correlated with conditions during the past 2 or even 3 growing seasons. In this case, the large leaves might result from a combination of very warm weather two years ago and high rainfall this year. Another thing to consider, has the nutrient status of the trees environment changed? Did a river flood nearby, or has the area been fertilized somehow?

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