Making Sense of Marcescence

I pass a stand of woods on my drive to work that reminds me of fall even in mid-January. This is thanks to the large number of beech and ironwood trees that cling to their leaves long after those of other trees have fallen. Which has me wondering: just what biological reason prompts leaf retention?

_ASR8240 beech leaves 6x300

Because there is assuredly a reason. While homo sapiens sport frills that have no bearing on survival (think pink hair, nose rings, and spike heels), the majority of living organisms are strictly products of evolution, with physical adaptations fine-tuned to best ensure the continuation of their species.

Bringing us back to beeches. As it turns out, there’s a scientific term for leaf retention in deciduous trees: marcescence. Most common among oak species, witch hazel, ironwood, and American beech, the biological reason for marcescence is still a matter of speculation. One reason for leaf retention might have to do with nutrient cycling. Unlike leaves that fall in the autumn and decay on the forest floor, leaves that linger on branches through the winter retain and recycle their nutrients for themselves. Marcescent leaves may ward off browsing animals by concealing buds or making them harder for browsers to nip. There is also speculation that marcescence may protect some species from water or temperature stress.

Whatever its reason, marcescence adds yet another layer of beauty to the already beautiful winter woods. With sunlight filtering through silvery branches, icy water rushing along the Blockston Branch, and dry leaves whispering in the clear air, the Arboretum’s woods invite and delight throughout the winter months. Plan a visit soon, before spring growth transforms the wintry landscape. And please, leave the spike heels at home.

by Jenny Houghton
Youth Program Coordinator




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