Why do trees have leaves?

[towjyt]

I have a Maple tree that drops it's seeds early in the spring, just as the leaves are starting to form.

 

The other day, I got to wondering, why leaves?

 

If the evolution of the Maple tree provided everything that the Maple tree needs to propagate it's species, why leaves? The seeds are already gone.

 

My wife said that perhaps the leaves provide shade which preserves moisture for the seeds take root, but I see no advantage in a young Maple tree sprouting in the very shade of it's parent--things will get pretty crowded that way.

 

Certainly the shade does provide a damp spot, but I think that the leaves use up more moisture that they preserve.

 

So, my question is, what evolutionary advantage do leaves provide for the Maple tree?

[Annemarie]

The seeds that get carried away by the wind or any natural reason, will be more sucessful. Surely the tree needs leaves to extract energy from the sun, but yes also to provide shade for roots. The tree would ideally like the largest surface area to absorb as much of the suns rays as possible, leaves are flat and large.

[YT2095]

mostly it`s about surface area, a leaf formation will allow more CO2 and moisture respiration per branch than any other configuration, cerainly any config I could come up with wouldn`t match its efficiency, the spacing also allows light to enter each helped along with the random wind paterns that will expose each long enough to work effectively.

[mezarashi]

I'm not sure if this is what you mean, but I think the topic applies for every leaf-growing tree. Generally for everything classified under the Plant Kingdom, "leaves" are important. That green stuff is the stuff that has chlorophyll, used to synthesize basic carbohydrates (energy) from carbon dioxide and water with the helping hand of sunlight. Which is also why leaves need to be broad and thin, to get maximum surface area exposed to sunlight.

 

During winter, I guess the trees go into a plant version of "hibernation" using stored energy. Another interesting thing to ponder though is why trees branch as they do. From trunk to main branches to smaller branches to twigs to leaves.

[YT2095]

Another interesting thing to ponder though is why trees branch as they do. From trunk to main branches to smaller branches to twigs to leaves.

 

again, it`s a surface area thing, what a fantastic way to maximise the effective area of capture for all the things it needs AND remain structuraly sound at the same time

[towjyt]

So, the leaves absorb co2 from the atmosphere and use sunlight as an energy source?

 

Sort of a combination of lungs and solar cell?

[Ophiolite]

The more pertinent question is why do trees have trunks? Answer:To get the leaves nicely exposed to the sunlight. It's back to YT's surface area. (Do you have a large surface area YT, or am I getting too personal? )

[YT2095]

kinda yeah

 

but also they allow the tree to respire, and so like your lungs, they`re Dual Function, they take IN what you need and expell what you don`t need, in the case of a tree it`s O2 (Oxygen) and Water as the "waste" product

[swansont]

If the evolution of the Maple tree provided everything that the Maple tree needs to propagate it's species' date=' why leaves? The seeds are already gone.

[/quote']

 

It's an advantage to drop some seeds next year, and the year after that, too. Leaves allow the tree the possibility to live until then.

[YT2095]

(Do you have a large surface area YT, or am I getting too personal? )

 

without definition, I cannot answer your latter question, if it`s of any help my BMI is less than 20.

How does this relate to Trees?

[Ophiolite]

Not in any way at all. I was just feeling devilish..

[YT2095]

aha! C2H5OH consumption again, ya just Gotta love those plants and little yeasty critters

[-Demosthenes-]

So' date=' the leaves absorb co2 from the atmosphere and use sunlight as an energy source?

 

Sort of a combination of lungs and solar cell?[/quote']

It doesn't absorb energy directly from sun. It creates sugars by spliting water and reacting it with CO2 using the energy from the sun. There are two types of reactions in a plant, the light reactions (photosynthysis) are the ones that make the sugar and the dark reactions (respiration) are the onces that use the sugar, much the way we use sugar, for energy. I'm pretty sure, been a long time since bio...

[YT2095]

it DOES absorb energy directly from light! it uses it as the activation energy Directly so that photosynthesis may take place.

[reverse]

And in winter...the plant refuses to maintain the leaf structures as they are of reduced benefit...so it ejects them.

 

some plants are just leafs.

one plant is a really really massive leaf

the Ravenala from Madagascar.

 

And if you look at this plant long enough...you will see the answer to many other plant structure questions.

[Ophiolite]

Is that the one that flowers rarely, lives a very long time, and one of which can be found at Kew Gardens?

[reverse]

Is that the one that flowers rarely, lives a very [/b'] long time, and one of which can be found at Kew Gardens?

 

Possibly...it's a bit tatty looking now...is it on one of the corners directly beneath the radial hub point of the glass roof?

[atinymonkey]

Er, the Ravenala is a Palm and does not flower: -

 

http://www.pacsoa.org.au/places/Kew/InteriorB.html

 

I think Ophiolite is thinking of the Titan Arum, which has only flowered 5 times since 1889: -

 

http://www.huntington.org/BotanicalDiv/TitanArum.htm

http://news.bbc.co.uk/1/hi/sci/tech/401124.stm

(Kew's link seems to be down at the moment)

[-Demosthenes-]

it DOES absorb energy directly from light! it uses it as the activation energy Directly so that photosynthesis may take place.

I meant that the sunlight energy isn't taken in driectly and used for the plant's energy.

[Ophiolite]

I'm slightly confused Demosthenses: in what sense is the energy not taken in directly? There is no system that I know, mechanical or biological, that does not perform some form of conversion of energy before it is used.

[Mokele]

The photon knocks a high-energy electron off a magnesium (iirc) atom, and the electron is passed to various protiens (which have some other form of metal in them, often iron), generating ATP as the electron's energy is lost. Given that ATP is pretty much the universal currency for cellular energy (though other chemicals are also used, such as GTP and NADH), I'd say that yes, a plant is definitely directly taking in energy (the photon) and pumping out cellular energy.

 

Mokele

[-Demosthenes-]

I meant that there were other things involved, the sunlight doesn't run the plant alone, there is stuff in between.

[YT2095]

as a direct energy source it does though