An important factor in counting the number of leaves on a tree is
time of year. Since Daniel is posting in fairly decent English, he

Thanks for the flowers.

is likely in a north temperate area. If he would wait till some time
in December, the easy answer to his question would often be 'none'.
However, a quick scan and guess of the 25 year old mulberry tree
outside my window looks like perhaps about 50 thousand leaves. I
would expect that a large Giant redwood would have several million
leaves.

I thought about giving the background of my question when opening the
thread but I decided not to do it, due to the fact that I wanted more
biological oriented answers.

Beside the fact that I was simply curious if there exist reasonable
estimates about the maximum amount of leaves/needles of trees my focus
was on realistic graphical representation of trees. Most tress I have
seen in computergraphics are among the poorest objects.
A good representation could aim to draw at least one triangle per
leave and let them swing in the wind.

I am pretty sure that nobody ever "counted" the leaves of large trees,
but there should be reasonable estimates for their amount.
e.g. collect all the leaves in autumn for a standalone tree and weigh
them. Maybe some inside bilogical knowhow as described in one of the
threads could help. Up to now I have seen some guesses. Isn't there
some scientific work
about this topic?
How is the amount of the oxygen/carbon dioxid turnover estimated?
Wouldn't it make sense to have some O_2 capacity estimate for leaves
of
different trees?

thanks for your posts, daniel