Topic: Deciduous Plants retaining their foliage

[Garden Manager]

I was wondering under what circumstances a plant that normaly looses its leaves in the winter would either keep them or hold onto the leaves for longer than normal.

i am aware of beech and hornbeam used as hedges keeping the old leaves (this because trimming promotes juvenile growth which retains is leaves). But are there any other examples? ie you cut it back hard and it stays nearly evergreen?

I have a forsythia which I hard pruned after flowering this year. it has not only retained its foliage, but the foliage has remained green and healthy even after recent cold weather. Is this a fluke or can this happen sometimes?

[jennym]

I believe the temperature and light levels have a lot to do with activating hormones within the plant which cause it's leaves to change colour and fall. Each plant is different. And I would imagine aging, too, because even evergreen plants lose their leaves, albeit not in one go. Funnily enough, I was thinking to myself today that the autumn leaves appear to be staying on the trees longer this year, the main road through Epping Forest is splendid right now.

There is some basic info on this link:
http://www.naturenorth.com/fall/colors/color5.html
and more in depth info on these links:
http://scidiv.bcc.ctc.edu/rkr/Botany110/lectures/leaves.html
http://www.puc.edu/Faculty/Gilbert_Muth/botlec07.htm

[beejay]

I have noticed this year that leaf fall has been rather strange. I have put it down to the weather that we had earlier in the autumn so that there did not seem to be any "proper" autumn colours. I have a flowering cherry that has only just lost its leaves which is much later than normal & there was not much change in colour when it often has some lovely tints.

[Mrs Ava]

Altho our weeping willow has shed half of it's leaves, it is still looking incredibly green and healthy.  My cornus shed all of their leaves weeks and weeks ago!  And my fushcia is still not only green, but in flower, and today I noticed I have digitalis lutea in flower in the garden!!  Our medlar tree is also still in leaf, which is rather disappointing as one of the many glories of the medlar tree is the bright autumn foliage colour!  And last but by no means least, our apple trees, all 5 of them, still have leaves and fruit!  My concern is, will the trees be less vigourous next year as they haven't reabsorbed food from this years leaves yet?!

[Ceratonia]

I have noticed this year that leaf fall has been rather strange. I have put it down to the weather that we had earlier in the autumn so that there did not seem to be any "proper" autumn colours.

There's an interesting display in the University Botanic Garden here in Cambridge, explaining all the science behind autumn leaf colour in easily understandable terms, with lots of different examples growing nearby. Cold autumns do produce a more colourful display than warmer ones.

Dead leaves which are retained on the tree through winter are called "marcescent" leaves. Beech, hornbeam and oak are the most common examples of trees which do this, as has already been said.

I reckon Garden Cadet's forsythia is biding its time and will drop its leaves if the weather stays cold. Mine also has most of its leaves still and hasn't been pruned for years. Forsythia has some interesting temperature responses  - you can play tricks to make it flower at the wrong time - a warm spell after first frost will make it start flowering, so people have been known to artificially chill or warm it for this purpose.

The plant hormones auxin and abscissic acid make an "abscission zone" which cuts of the supply of nutrients to the leaf and it takes a while for this process to happen. Hormone levels will be affected by a hard pruning. Interesting fact - synthetic versions of these hormones were used by the Americans in Vietnam as defoliants - Agent Orange!

[Garden Manager]

Yes it has certainly been a strange year for leaf fall. Some trees still with leaves yet others dropped weeks ago. Even in the same genus of plant! There are prunus (ornamental cherry) on the public green in front of our house that shed aages ago (one always seems to drop in mid october regardless of the weather), yet our nextdoor neighbours have one of those ornamental cherries with pink double blossom in late spring (Japanese cherry i think) which is only now loosing its leaves.

I suppose soil conditions make a difference, the 'green' is used as a recreation area so the soil is probably more compacted than in a private garden, but even taking this (and differing species/cultivars) it is a considerable difference in time.

Going back to the forsythia, it looks like it wont be leafless for long before it comes into flower next spring!

[undercarriage plan]

Walking back from school run the other day, saw my first tree just drop all its leaves in about 10 mins, was most perculiar, though it was when we'd had that really hard frost the night before.....Just stood there watching with me matey, we're easily entertained..

[Robert_Brenchley]

Most of my apples have dropped their leaves but the Bramley still has it's.

[jennym]

Most of my apples have dropped their leaves but the Bramley still has it's.

Exactly the same here, Robert!

[flowerlady]

I still have coloured foliage on a variegated salix, and even a rose blooms!

It does make you wonder if the trees know something we don't!! Like a monster winter?   :-\   It was about 20 years ago when we had the last one.

[Icyberjunkie]

I always thought that the leaf drop and colour was a result of the plants not getting enough water and nutrients due to frozen conditions and low light levels - so slow respiration.  As a result the leaves stop functioning and dry out helped the high winds. 

[john_miller]

I was wondering under what circumstances a plant that normaly looses its leaves in the winter would either keep them or hold onto the leaves for longer than normal.

One circumstance that has occured here this year and affected leaf drop was our extremely warm summer and early autumn. Measured as time and temperature above 15C our summer was 50% warmer than the average measured over the past century. Typically foliage will start to turn North of here first near the Canadian border, about 150 miles, or at high elevations in the Adirondack State park, 'peak' (when almost all the trees are showing their most dazzling levels of autumn colour) colour will be in mid-September and this peak will migrate South so that we typically have peak in this area around the 10th of October (and luckily for our tourist dependent businesses), tending to coincide with a public holiday over here.
In a radio interview I heard a N.Y. State, where the Adirondack park is, plant botanist mention that the leaves in the park were turning a month late. Down here we didn't hit peak until roughly 25th Oct. (not that peak was very good as we didn't get the concentrated leaf turn that we normally get and the heat suppressed the production of anthocyanins so that the 'reds' this year were relatively anaemic). This was put down entirely to the heat earlier this year.
If anyone needs help, Adirondack is pronounced Add-e-ron-dak. 

[Robert_Brenchley]

I always thought that the leaf drop and colour was a result of the plants not getting enough water and nutrients due to frozen conditions and low light levels - so slow respiration.  As a result the leaves stop functioning and dry out helped the high winds. 

It's a lot more complex than that. I'm no botanist,m but apparently as the day length diminshes they extract nutrients from the leaves, then seal off the stalk so the wound doesn't bleed when it falls.

[Mrs Ava]

Trees are all now nude in our garden!

[flowerlady]

Our silver birch has still got leaves on it!! Very inconvenient of it as I want to hang lights off it   :D

Reading this thread has me in awe.  Some on you guys are so knowledgeable.  Do you all have horticultural qualifications by any chance?

[Garden Manager]

The forsythia is finaly loosing its leaves, but it hasnt realy changed colour which is a bit strange.

Another thing i noticed whilst out walking yesterday is that the brambles in the hedgerows seem to be holding onto their leaves a long time this year. :o

[Ceratonia]

Another thing i noticed whilst out walking yesterday is that the brambles in the hedgerows seem to be holding onto their leaves a long time this year. :o

I think Blackberries are classified as 'semi-evergreen' ie under the right conditions it can keep its leaves all year round.

[Jesse]

Walking back from school run the other day, saw my first tree just drop all its leaves in about 10 mins, was most perculiar, though it was when we'd had that really hard frost the night before.....Just stood there watching with me matey, we're easily entertained..

Similar thing happened here, the oak tree was full of autumn leaves, I had been looking at it the one day thinking to myself that the leaves were staying much longer than usual and thought it was down to having very still weather, next day coming home from school run in the morning the tree was bare and a carpet of leaves on the ground around it, was quite strange and almost magical. :)

[Ceratonia]

Got the Cambridge Botanic Garden newsletter yesterday and there's an article about how it's been an unusual autumn for falling leaves. Most of the points made by the "professionals" were the same as this thread.

Apparently sun hitting the frozen foliage can cause some trees to shed all of their leaves within an hour and this tends to happen a lot at temperatures of -5C or below.

It also mentions that there was a very mild October (over 20C on Oct 31) and no frost until 18 Nov, but then a very hard frost (-4C) and that many trees dropped green summer leaves as a result. Forsythia was singled out as one of the plants which wasn't really affected  - Magnolia, Tilia & Acers being others.

One other unrelated statistic in this article, was that more rain fell in a forty minute thunderstorm on September 9 than in the whole of March or April. So much for April showers.

[Jesse]

This thread reminded me of a poem I found recently, thought I'd share it:

The Foolish Fir Tree - A Christmas Poem by Henry Van d**e

"A tale that the poet Ruckert told
To German children, in days of old;
Disguised in a random, rollicking rhyme
Like a merry mummer of ancient time,
And sent, in its English dress, to please
The little folk of the Christmas trees."

A Little fir grew in the midst of the wood
Contented and happy, as young trees should.
His body was straight and his boughs were clean;
And summer and winter the bountiful sheen
Of his needles bedecked him, from top to root,
In a beautiful, all-the-year, evergreen suit.

But a trouble came into his heart one day,
When he saw that the other trees were gay
In the wonderful raiment that summer weaves
Of manifold shapes and kinds of leaves:
He looked at his needles so stiff and small,
And thought that his dress was the poorest of all.
Then jealousy clouded the little tree's mind,
And he said to himself, "It was not very kind
"To give such an ugly old dress to a tree!
"If the fays of the forest would only ask me,
"I'd tell them how I should like to be dressed,
"In a garment of gold, to bedazzle the rest!"
So he fell asleep, but his dreams were bad.
When he woke in the morning, his heart was glad;
For every leaf that his boughs could hold
Was made of the brightest beaten gold.
I tell you, children, the tree was proud;
He was something above the common crowd;
And he tinkled his leaves, as if he would say
To a peddler who happened to pass that way,
"Just look at me! don't you think I am fine?
"And wouldn't you like such a dress as mine?"
"Oh, yes!" said the man, "and I really guess
I must fill my pack with your beautiful dress."
So he picked the golden leaves with care,
And left the little tree shivering there.

"Oh, why did I wish for golden leaves?"
The fir-tree said, "I forgot that thieves
"Would be sure to rob me in passing by.
"If the fairies would give me another try,
"I'd wish for something that cost much less,
"And be satisfied with glass for my dress!"
Then he fell asleep; and, just as before,
The fairies granted his wish once more.
When the night was gone, and the sun rose clear,
The tree was a crystal chandelier;
And it seemed, as he stood in the morning light,
That his branches were covered with jewels bright.
"Aha!" said the tree. "This is something great!"
And he held himself up, very proud and straight;
But a rude young wind through the forest dashed,
In a reckless temper, and quickly smashed
The delicate leaves. With a clashing sound
They broke into pieces and fell on the ground,
Like a silvery, shimmering shower of hail,
And the tree stood naked and bare to the gale.

Then his heart was sad; and he cried, "Alas
"For my beautiful leaves of shining glass!
"Perhaps I have made another mistake
"In choosing a dress so easy to break.
"If the fairies only would hear me again
"I'd ask them for something both pretty and plain:
"It wouldn't cost much to grant my request,
"In leaves of green lettuce I'd like to be dressed!"
By this time the fairies were laughing, I know;
But they gave him his wish in a second; and so
With leaves of green lettuce, all tender and sweet,
The tree was arrayed, from his head to his feet.
"I knew it!" he cried, "I was sure I could find
"The sort of a suit that would be to my mind.
"There's none of the trees has a prettier dress,
"And none as attractive as I am, I guess."
But a goat, who was taking an afternoon walk,
By chance overheard the fir-tree's talk.
So he came up close for a nearer view;
"My salad!" he bleated, "I think so too!
"You're the most attractive kind of a tree,
"And I want your leaves for my five-o'clock tea."
So he ate them all without saying grace,
And walked away with a grin on his face;
While the little tree stood in the twilight dim,
With never a leaf on a single limb.

Then he sighed and groaned; but his voice was weak
He was so ashamed that he could not speak.
He knew at last that he had been a fool,
To think of breaking the forest rule,
And choosing a dress himself to please,
Because he envied the other trees.
But it couldn't be helped, it was now too late,
He must make up his mind to a leafless fate!
So he let himself sink in a slumber deep,
But he moaned and he tossed in his troubled sleep,
Till the morning touched him with joyful beam,
And he woke to find it was all a dream.
For there in his evergreen dress he stood,
A pointed fir in the midst of the wood!
His branches were sweet with the balsam smell,
His needles were green when the white snow fell.
And always contented and happy was he,
The very best kind of a Christmas tree.