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The world's second-largest known tree, the President, in Sequoia National Park is 3200 years old and is said to have 2 billion leaves (Source: https://youtu.be/vNCH6uhB_Bs?t=59).

Is this correct? And how was this number arrived at?

In other words, how is such an insanely large number possible?

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    $\begingroup$ The US National Park Rangers count them. But that makes it a mathematical question, not a biological one, so it should be obvious that it is off topic here. $\endgroup$ – David Jan 18 at 21:34
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    $\begingroup$ Strictly speaking, S. giganteum is a conifer so it has needles, not leaves. So count the individual needles on one twig (they're really small), multiply by the number of twigs per branch and the number of branches on the tree. $\endgroup$ – jamesqf Jan 19 at 18:14
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    $\begingroup$ @David That number was obviously not 'counted'. It was arrived at by an estimate based on botanical facts. $\endgroup$ – Ritesh Singh Jan 19 at 19:59
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    $\begingroup$ Botanical facts? I imagined they extrapolated from the empirical observations of the numbers of leaves per branch and the number if branches per metre rise in the trunk, allowing for the pattern of sub-branching. But it is hardly a question of biological principle. As I have indicated, it may be answered by some general mathematical formula, if you plug in the constants. A good scientific exercise, but not a question likely to find interest or answer here, I would imagine. $\endgroup$ – David Jan 19 at 20:24
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    $\begingroup$ @RiteshSingh, I upvoted your question. As a physicist that's a member of a lot of Stack exchanges, I wonder if you could help us by committing to the Materials Modeling proposal? We really need help, and would very much appreciate if you could commit! $\endgroup$ – user1271772 Jan 21 at 3:50
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One way* to come up with an estimate of how many leaves - or needles, in the case of Sequoiadendron giganteum - is simply to count the number of leaves on a twig (or a number, to get a good average), then the number of twigs on a branch, and then count the branches on the tree, after which it's just multiplication.

Now one reason that the number seems so high is the way the needles grow. Unlike for instance pines, which have long needles arranged in sparse clusters of 2, 3, or 5, or spruce & fir, which have medium needles arranged along the branches, the sequoia has lots of tiny needles arranged on twiglets.

Link with picture of sequoia needles: https://www.monumentaltrees.com/en/trees/giantsequoia/giantsequoia/ Picture of pine vs spruce & fir: https://www.finegardening.com/article/fir-vs-spruce-vs-pine-how-to-tell-them-apart

*But I don't know whether it's the way used to get the number in the link.

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  • $\begingroup$ Thank you for the pics. This answer completely satisfies by curiosity! :) $\endgroup$ – Ritesh Singh Jan 25 at 11:22

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