Why a huge number of trees/plants have cylindrical stems? I have been told that this question's answer lies in Physics but I don't know where to find. Can any one help?

  • $\begingroup$ Short answer: not all do. Many tree trunks are fluted, especially at the base. Then there's the Blue Ash (raxinus quadrangulata) which gets its botanical name from its square stems. $\endgroup$
    – jamesqf
    Apr 7 '16 at 19:18
  • $\begingroup$ @ jamesqf Thanks for reply. I have edited my question taking your answer in account. But your answer raises an interesting question , why * Blue Ash (raxinus quadrangulata)* is an exception? $\endgroup$
    – Arpon Basu
    Apr 8 '16 at 6:16

1) You know most bridges have vertical cylindrical pillars.

This is probably because cylinder is among the strongest 3D structures to support anything. So, cylindrical trunk provide best support for tree crown.

2) Most accurate It is natural for any cell to grow equally in all directions. This, leads cells to expand in all directions equally in a circular girth.

3) Resistance Cylindrical girth provides least resistance to air. So, tree naturally takes this shape to prevent damage by air strikes.

4) Read https://m.reddit.com/r/askscience/comments/1973mh/

for more info.

5) http://www.stevespanglerscience.com/lab/experiments/balancing-act-cylinder-strength/

for strength of Cylinders.

  • $\begingroup$ No. Most bridges do not have cylindrical beams. Angles, channels, built up girders seem most common for bridge beams. $\endgroup$ Apr 8 '16 at 8:55
  • $\begingroup$ stevespanglerscience.com/lab/experiments/… $\endgroup$ Apr 8 '16 at 9:05
  • $\begingroup$ @curious_cat I meant pillar. Thiss was pillar I first saw on search. t1.gstatic.com/… $\endgroup$ Apr 8 '16 at 9:12
  • $\begingroup$ I think you have the air resistance thing backwards. Look at pictures of trees growing where there are strong prevailing winds (coasts, mountain tops, &c), and you'll see that they are markedly non-cylindrical. The growth part seems intuitive: trees grow (in diameter) by adding to a thin layer (the cambium, IIRC) under their bark. In the absence of any outside force, every part of that layer is likely to grow at the same rate, so you get a cylinder. $\endgroup$
    – jamesqf
    Apr 8 '16 at 18:09
  • $\begingroup$ @jamesqf Trees in costal and mountains are rather more cylindrical and straight (less branched) than at plains. I am writing from my experience from Himachal, Jammu, Goa, and Mumbai $\endgroup$ Apr 9 '16 at 7:36

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