[sampo]

In forestry, they teach that as "pipe model". I am unable to track down how long that observation has been known in forestry, but I found this 1964 paper that attempts to build on the observation (already known in 1964) and build a theory.

https://www.ncbi.nlm.nih.gov/pubmed/29370362

The modern understanding is that the pipe model holds only approximately.

[sampo]

It's kinda nice, how you can take a bunch of metal wires to make a tree trunk, and start separating them and folding them into branches, and separating and folding into smaller branches, and this can give pretty realistic looking trees.

https://diyjoy.com/wp-content/uploads/2016/06/WireTree.jpg

https://www.thisiscolossal.com/2014/10/dense-wire-tree-sculp...

https://www.youtube.com/watch?v=g0tj_ZLpv80