>>14172231A "why" question is hard to answer. I'm not a tree, but I have worked extensively enough with plants to explain the reasoning for the patterns you see.
It has to do with the path of least resistance and efficiency of growth. A tree naturally will grow irrationally so that it can maximize its rate of growth. Limbs will not grow straight because the light and shadows hitting them are never the same. Also wind and animals affect their growth, but even a "straight" tree is always curved in some form.
When growing they oscillate too, they are never still because the of the water in them coming from the ground. The water moves due to surface tension and the plants cells carrying it too. The oscillation of the sun by proxy is also causing the plant hormone auxin to react with it so you get "spiral growth patterns" as a result.
