Architecture of trees

I have been reading 'A Bigger Message-Conversations with David Hockney'. There is a lot of chat about trees in this book. I like the bit about comparing trees to buildings- 'A cathedral or mosque is built it does not grow.........As it grows the tensions and stresses alter, but it must always arrange itself so as to accommodate them. The tree is, indeed, much more complex, than human architecture.
These London Planes made me think of this problem of design, architecture and growth.