Sign up ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

Why does the trees grow circular? What are the forces that force a plant to grow with a circular trunk? If the stability of the tree were the reason then why does the trees bend in their natural growth? Silly question isnt it??

share|cite|improve this question

closed as off-topic by Jim, John Rennie, Kyle Kanos, DavePhD, BMS May 15 '14 at 17:16

  • This question does not appear to be about physics within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

there are no forces that make it grow circular. it is more a lack of anything to make it grow some other way. When trees grow, they add more tree equally on all sides. That process naturally leads to a cylindrical shape – Jim May 15 '14 at 15:37
This question appears to be off-topic because it is about biology and might find a better home on biology.SE – Jim May 15 '14 at 15:39
@Jim a tree growing equally to all sides would naturally lead to a hemi-spherical tree (taking the floor into account), not a cylindrical one. Up is preferred over sideways to catch sufficient light for photosynthesis. - But I agree that this is more biology than physics – Michiel May 15 '14 at 15:52
@Michiel seeing as the question specified "circular shape", I assumed that it was implied that we were looking at a transverse cross-section when I said "equally on all sides". Obviously, the tree grows quicker vertically than any perpendicular direction, as it is highly incentivized. – Jim May 15 '14 at 15:56
I don't think this question is as restricted to biology as it appears. You could see similar tendency towards circular cross section if you painted a strand of wire with a very large number of coats of paint. Even starting with wire of square cross section, the successive layers of paint would tend towards circular cross section. No biological control is required, just the process of growth in layers. – trichoplax Jun 4 '14 at 15:25

1 Answer 1

I don't think it's clearly physics, but ...

The same shape assumes your head or your hand or ...

Circle (sphere) is the most efficient as regards the proportions of the "content" and the "skin". Any other shape requires more protective cover to hold the same amount of "content". And protecting the body from the outside world is the most important function of skin or bark or whatever. Another function is holding water inside, and again, the smaller the area of the cover, the less water evaporates.

There are probably other important reasons, but they would all be based on efficiency

Now, how does the tree know it? It doesn't. It's the survival of the fittest ...

share|cite|improve this answer
Yes "how does the tree know it???" that was the question that ultimately questions us. That is why my question was what are the forces that force a plant to grow circular. Any ways its too more hypothetical question considering the fact that the very existence of life is a mystery. – Rams May 15 '14 at 17:03
I answered this - "survival of the fittest" means evolution. – bright magus May 15 '14 at 17:08

Not the answer you're looking for? Browse other questions tagged or ask your own question.