Marcescence: Or the Phenomenon of Leaf Retention in Some Deciduous Trees

Marcescence: Or the Phenomenon of Leaf Retention in Some Deciduous Trees

Already, the celebrations of Christmas feel long gone. We have returned to work at Capital Gardens. For the store, January means dismantling Christmas displays, stocktaking, and making space for the imminent arrival of a major plant delivery from Italy. For me, the challenge is to try and get (or at least feel) healthier. That is to say, to make amends for festive overindulgence. What happened to all those good intentions before Christmas? To quote Britney Spears, “Oops!…I Did It Again”. One healthy tradition I follow, and even enjoy, is taking a postprandial Christmas walk. Dr Google suggests that walking after a heavy meal offers certain health benefits, such as stimulating the stomach and intestines, improving blood sugar control, and reducing bloating.  However, according to a study by the Queensland University of Technology in Brisbane, an average person would need to walk about 4 miles to burn up the calories from a single mince pie – that’s like walking from Wood Green tube station to Alexandra Palace Garden Centre (maybe stopping to admire the remaining coppery leaves on the lower branches of the beech tree in our nature area) and then striding back to the station! The whole Christmas dinner plus two glasses of wine would require a trek of 12.8 miles, which is roughly equivalent to walking from Alexandra Palace Garden Centre to our sister branch, Neal’s Nurseries Garden Centre in Wandsworth. I walked a mere 3 miles after my Christmas lunch, only enough to burn off a single serving of turkey and roast potatoes, but miraculously, it gave me the appetite to tuck into a big plateful of leftovers upon returning home!

I live close enough to Alexandra Palace Garden Centre to have the option of walking into work in the morning. However, my daily commute is usually a challenging affair. Revving traffic on congested roads, yelling hordes of school children, and sidestepping speeding scooters and baby strollers. In contrast, my Christmas perambulation was calm and contemplative. One thing that engaged my interest was the rattling sound of the dry leaves of the hornbeam hedge as I followed Albert Road around the local recreation ground. Continuing my walk up The Avenue towards Alexandra Palace, I noticed that the beech hedges still retained their crisp brown leaves, unlike the mature beech trees in the Palace grounds that had shed them in autumn. These observations made me ponder, ‘why do only some deciduous trees keep their dead leaves while others don’t? Why do hornbeam and beech grown as hedges hold on to their leaves, when as large trees they might only retain them on a few lower branches?’ I decided to do some research.

While most deciduous trees and shrubs shed their leaves as a strategy to survive the cold winter months, some retain their foliage for an extended period. This phenomenon is known as marcescence (from the Latin, marcescere = to fade). Marcescence occurs in various deciduous tree species, particularly in temperate climates like ours. Marcescence describes this retention of dead leaves on deciduous trees well into the winter months, long past the usual leaf-drop period. You will be familiar with marcescence if you have ever admired the burnished copper tones of a beech hedge in winter. So, why do some deciduous trees exhibit marcescence? The truth is that nobody really knows the answer. The exact reasons are still being investigated by scientists, but several theories have been proposed to help explain this leafy persistence.  The most popular explanation is that it helps deter winter herbivores from grazing the nutritious shoots by bulking them out with low nutrition dried leaves. Another proposal is that retaining dead leaves may help protect the dormant buds located at the base of the old leaves. By keeping its withered leaves attached, a tree may shield new buds from frost or desiccation. Additionally, dead leaves could act as insulation, providing an extra layer of warmth for delicate buds during cold weather. It has also been noted that marcescence plays an important role in the ecosystem by providing shelter and food for various organisms during the winter months. Old leaves remaining on deciduous trees and hedges provide a source of nutrients as well as a valuable winter refuge for many invertebrates and their eggs and larvae.  Small birds such as finches, tits, and sparrows, and small mammals such as bats, can find shelter amid the desiccated leaves from the cold and predators. Additionally, the dead leaves provide small birds with a larder to forage for insects and other food hidden among the retained leaves, helping them sustain themselves through the lean winter period. In return, bird droppings may help fertilize sheltering trees and hedges. So, marcescence offers some benefits to the tree and the ecosystem, but it may also have some potential drawbacks which might explain why mature trees tend not to exhibit marcescence. Retained leaves could provide an overwintering ground for fungal diseases or pests, which may affect the overall health of a tree. Another explanation is that there is no need to retain dead leaves higher than where browsing deer can reach.

In conclusion, marcescence is a curious phenomenon observed in certain deciduous trees, where dead leaves remain into the winter months. While the exact reasons behind this behaviour are still subject to debate, marcescence serves an essential ecological function, providing food and shelter for wildlife during harsh winters. So, when you come across a tree with lingering brown leaves this month, take a moment to appreciate the beauty and complexity of nature’s adaptations.

Further reading:

https://www.theguardian.com/lifeandstyle/2008/dec/19/christmas-foodanddrink

https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.4410

Already, the celebrations of Christmas feel long gone. We have returned to work at Capital Gardens. For the store, January means dismantling Christmas displays, stocktaking, and making space for the imminent arrival of a major plant delivery from Italy. For me, the challenge is to try and get (or at least feel) healthier. That is to say, to make amends for festive overindulgence. What happened to all those good intentions before Christmas? To quote Britney Spears, “Oops!…I Did It Again”. One healthy tradition I follow, and even enjoy, is taking a postprandial Christmas walk. Dr Google suggests that walking after a heavy meal offers certain health benefits, such as stimulating the stomach and intestines, improving blood sugar control, and reducing bloating.  However, according to a study by the Queensland University of Technology in Brisbane, an average person would need to walk about 4 miles to burn up the calories from a single mince pie – that’s like walking from Wood Green tube station to Alexandra Palace Garden Centre (maybe stopping to admire the remaining coppery leaves on the lower branches of the beech tree in our nature area) and then striding back to the station! The whole Christmas dinner plus two glasses of wine would require a trek of 12.8 miles, which is roughly equivalent to walking from Alexandra Palace Garden Centre to our sister branch, Neal’s Nurseries Garden Centre in Wandsworth. I walked a mere 3 miles after my Christmas lunch, only enough to burn off a single serving of turkey and roast potatoes, but miraculously, it gave me the appetite to tuck into a big plateful of leftovers upon returning home!

I live close enough to Alexandra Palace Garden Centre to have the option of walking into work in the morning. However, my daily commute is usually a challenging affair. Revving traffic on congested roads, yelling hordes of school children, and sidestepping speeding scooters and baby strollers. In contrast, my Christmas perambulation was calm and contemplative. One thing that engaged my interest was the rattling sound of the dry leaves of the hornbeam hedge as I followed Albert Road around the local recreation ground. Continuing my walk up The Avenue towards Alexandra Palace, I noticed that the beech hedges still retained their crisp brown leaves, unlike the mature beech trees in the Palace grounds that had shed them in autumn. These observations made me ponder, ‘why do only some deciduous trees keep their dead leaves while others don’t? Why do hornbeam and beech grown as hedges hold on to their leaves, when as large trees they might only retain them on a few lower branches?’ I decided to do some research.

While most deciduous trees and shrubs shed their leaves as a strategy to survive the cold winter months, some retain their foliage for an extended period. This phenomenon is known as marcescence (from the Latin, marcescere = to fade). Marcescence occurs in various deciduous tree species, particularly in temperate climates like ours. Marcescence describes this retention of dead leaves on deciduous trees well into the winter months, long past the usual leaf-drop period. You will be familiar with marcescence if you have ever admired the burnished copper tones of a beech hedge in winter. So, why do some deciduous trees exhibit marcescence? The truth is that nobody really knows the answer. The exact reasons are still being investigated by scientists, but several theories have been proposed to help explain this leafy persistence.  The most popular explanation is that it helps deter winter herbivores from grazing the nutritious shoots by bulking them out with low nutrition dried leaves. Another proposal is that retaining dead leaves may help protect the dormant buds located at the base of the old leaves. By keeping its withered leaves attached, a tree may shield new buds from frost or desiccation. Additionally, dead leaves could act as insulation, providing an extra layer of warmth for delicate buds during cold weather. It has also been noted that marcescence plays an important role in the ecosystem by providing shelter and food for various organisms during the winter months. Old leaves remaining on deciduous trees and hedges provide a source of nutrients as well as a valuable winter refuge for many invertebrates and their eggs and larvae.  Small birds such as finches, tits, and sparrows, and small mammals such as bats, can find shelter amid the desiccated leaves from the cold and predators. Additionally, the dead leaves provide small birds with a larder to forage for insects and other food hidden among the retained leaves, helping them sustain themselves through the lean winter period. In return, bird droppings may help fertilize sheltering trees and hedges. So, marcescence offers some benefits to the tree and the ecosystem, but it may also have some potential drawbacks which might explain why mature trees tend not to exhibit marcescence. Retained leaves could provide an overwintering ground for fungal diseases or pests, which may affect the overall health of a tree. Another explanation is that there is no need to retain dead leaves higher than where browsing deer can reach.

In conclusion, marcescence is a curious phenomenon observed in certain deciduous trees, where dead leaves remain into the winter months. While the exact reasons behind this behaviour are still subject to debate, marcescence serves an essential ecological function, providing food and shelter for wildlife during harsh winters. So, when you come across a tree with lingering brown leaves this month, take a moment to appreciate the beauty and complexity of nature’s adaptations.

Further reading:

https://www.theguardian.com/lifeandstyle/2008/dec/19/christmas-foodanddrink

https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.4410