This is the retention of the dead and dry leaves (and sometimes other parts such as fruit or seed pods) on some deciduous trees through winter. Persistence, or as I like to think of it: a relentless lingering, somewhat along the lines of my cat’s queries for elevenses, twelveses, oneses, twoses (you get the idea). Some trees seem to exhibit marcesence as a trait – oaks are apparently one of them, although our climate isn’t mild enough for most Quercus spp. so I can’t perform a decent study on multiple varieties. I did take a wander past the row of bur oaks (Q. macrocarpa) that grow near the train station in my neighbourhood, and while there were a few single leaves straggling on the branches, the trees were pretty much completely bare. But we have to count that as an insufficiently representative sample (which, incidentally, also seems to be my cat’s views on the amount of food I give her).
There are several theories on what causes marcescence, and what purpose it serves. I believe in the case of this elm tree (and others like it in our city), the early frosts and severe cold we received back in September led to a failure of the formation of the abscission zone. (This is an area of separation created by the natural weakening of cell walls between the petiole and the leaf. While deciduous trees abscise in autumn, conifers do it pretty much all the time. Another big difference is that deciduous trees normally fling everything off and conifers are, well, waaaaaaay more reserved). The leaves in my photo basically died on the spot and the tree wasn’t quite ready for that to happen. The wind took most of them off but some are still hanging around, waiting for spring like the rest of us.
Some researchers speculate that marcescence is a defense mechanism for the tree, protecting it from the munching of herbivorous predators such as moose and deer (who are going to eat fresh, tender young branch tips over icky dry foliage every time. You can’t blame them, really). Another idea is that the dry leaves act like little windproof shawls for the leaf buds, protecting them from winter desiccation. Perhaps. Still another thought is that the trees are deliberately generating their own mulch, dropping it at just the right time – spring, not autumn – for maximum moisture retention and as a source of nutrients. Far-fetched? Maybe, maybe not.
So what happens in the spring, when the buds of the new leaves break? The marcescent leaves may remain on the tree, still waiting for a really strong wind to snap them off, or they may be pushed off the tree by the new growth, in which case they are instantly sucked up into a magical vortex so that you never have to rake them up.
Then again, there are never any guarantees when it comes to magic, so have that rake handy, just in case.
I never knew there was a term for this. Should have guessed there would be, but it’s nice to know. I’ll use it.
It’s one of those things that you might notice but not really give much thought…you’d never guess that there is a word to describe it.
This is what makes valley oaks so messy through winter. They can defoliate thoroughly if they get cold enough. For sweetgum, retention of colorful foliage as late as possible is a desirable trait. It gets cool enough for them to color well here, but not cold enough to ruin the foliage. However, I think it can look odd if they are still colored late in winter. Some of ours are still rather green.
It is so interesting to hear experiences in different climates – you’re always very informative. Thanks so much for this!
I observe thus every year on our beech trees and beech hedge but never had a word for it. So thanks Sheryl! Personally I believe it has no function at all, or all beech would do it, wouldn‘t they? We have a row of them and only about half are completely bare, some shedding all their leaves really early. Look forward to learning more new words. 🙂
Yes, you’re right – it does seem interesting that not all of them do it…it doesn’t strengthen any of the reasoning behind it.
Bijzonder interessant en duidelijk
We have many trees here that hang on to their dead leaves which translates into we have to rake all winter.
A gardener’s work is never done…except if you live in our climate (but then we have to remove snow for almost five months out of the year!). 🙂
I, too, never knew there was a term for this, but all the oaks and beeches are a beautiful example of
marcescence. I’ve written it down so that I can look it at from time to time to remind myself of it. Now that I am in my sixties, my short-term memory isn’t as sharp as it once was. But if I write a word down and look at enough, eventually the meaning and the word will come together.
Oh yes – I read that beech trees often keep their leaves as well…we don’t have them here so I’ve never seen this. Would be rather pretty against the snow…. 🙂
We have them here, and they are pretty. Will get a picture of them soon.
I loved being introduced to this new word, and I loved that I already knew ‘abscission.’ Word by word, we learn. This was a fascinating post, and I’ll certainly look forward to more.
Thanks so much – I am so glad you enjoyed it! I had fun preparing it and hope I can maintain a weekly-ish schedule with them….
Good word, Sheryl. I know that here, beeches only retain their leaves through the winter when they are small or when they are used as a hedge and kept small on purpose. Young oaks do it as well.
You have many more trees there that do this than we do! I wish we could have beeches here…they are beautiful. It’s a fascinating observation that they tend to do this when they are young, and not as they age.
Wonderful post; and thank goodness for mysteries!
A note, Sheryl: the Share This by Email link does not seem to be working…
Thanks so much; I’m so glad you enjoyed it!
Thank you as well for letting me know about the email share link – I tested it and it seems to be working fine on my end, but I’ll see if I can get a few other people to try it from other email addresses (maybe it depends on the service provider?). It’s a WordPress feature so if it is truly acting up then I will have to contact them. Have a wonderful weekend!
An update: the email link seems to only be working for me! I will have WordPress take a look. Thanks so much for letting me know – I wouldn’t have checked this on my own and it could have gone on this way for a very long time.