The more random and unknown the pattern is the more you have to look to understand it and you can’t get more random than a pile of leaves. I always find it very interesting that no matter how random nature is, it never seems to make a mistake, it’s sort of a perfect chaos.
Painting that perfect chaos is very challenging also. I have to really look hard at a pile of foliage to be able to understand where to put the next stroke of paint. Besides the figure, I think foliage and flowers are the best training an artist can get. As I recall I believe John Singer Sargent said the same about flowers.