I feel that the first and third stages could do with a redrawing, but I will leave that to people better with lineart/anatomy than myself.
The second one has a mostly log-like shape, though, it is primarily the shading that I felt needed work, here is an example of wood shading, it definately isn't spectacular, but it may be something to use as a reference for your own design if you feel like using it.
EDIT: I also quickly redrew the leaf.
The second one has a mostly log-like shape, though, it is primarily the shading that I felt needed work, here is an example of wood shading, it definately isn't spectacular, but it may be something to use as a reference for your own design if you feel like using it.
EDIT: I also quickly redrew the leaf.