Leaves

[thyristor373]

Could anybody please give me the adress to a website where I can find some information about why the outer leaves on the branches are larger than the inner ones?

[MrMistery]

what are outer leaves and inner leaves? If you mean the leaves on the bottom of the branch as opposed to those near the top, then it's simply because they had more time to grow..

[thyristor373]

Yes, inner leaves are the ones at the bottom of the branch and the outer the ones at the to of the branch but the ones at the bottom must have had more time to grow than the ones at top. Then the effect would be the opposite. Besides this effect must disappear in the autu when the leaves fall off the tree.

[mith]

"inner" ones are more likely to be shaded(have less sunlight reaching them) and therefore it is more efficient to have larger ones at the edges.

[thyristor373]

On the other habd, if the "outer" ones are not that big the inner ones won't be that shaded.

[MrMistery]

I think it generally depends on the tree. For example, some plants have the leaves that first grow genetically programmed to be smaller(think, for example, at the bean stem). Others have all the leaves the same size.
Leaves, of course, do not have indeterminate growth, like stems and roots, so leaves won't grow larger and larger until they die. So, I think the best answer to your question is that various leaves are genetically encoded to be a certain size, with the reason varying on the way the leaves stick on the tree. Plus, leaf structure should also be taken into account: dorsi-ventral, inverse dorsi-ventral etc.