February 4th – I’ve always been puzzled why it might be that some deciduous trees don’t shed their dead leaves in autumn; the summer growth dies and goes brown, but doesn’t drop.
Someone asked the same question on social media over the weekend, so I thought I’d look into it.
The characteristic is called marcescence, and is exhibited mainly by oak, beech and hornbeam in the UK. It’s not clear what the evolutionary purpose of this curious feature is; it could be to shelter leaf buds from browsing animals like deer, and indeed, some oaks are only marcescent on lower boughs. Another theory says that the leaves attached to the beaches have their goodness absorbed back into the tree over winter, which is more efficient than them dropping and relying on conversion from leaf litter.
So I’m not really much wiser, but at least it has a name – and this marcescant oak was showing it’s dead leaves well beside the cycleway in Telford as I passed this morning, making me smile.