Patterns in nature. We perceive extraordinary beauty in patterns. Plants don't strive for beauty (unless we want to be very metaphysical about it). I am reminded of something I was told by Aranya who is a gifted teacher of the principles of Permaculture and all round polymath.

 He made the point that natural forms like shapes and patterns represent the most effective way of fulfilling a function. The thorny thistle does not exist to be beautiful for our eyes but nonetheless is extraordinarily beautiful.