Firstly, I must say that this picture offers a nice impact to the observer. It's original, neat and well drawn. I don't know how much time did you spend drawing this but the result is awesome. I love the different colors you used, all the green and brownish tones combine perfectly together.
The blank space has a strange form, if it was supposed to be a leaf, it doesn't look like it to me. Anyway it helps the eye to relax a bit because all the little leaves seem to follow a path which ends in the white shape. I like the concept and I recognize your big effort to color all the leaves, and it's quite interesting that some leaves are bigger than others.