This is located on the upper side of the blade or lamina of the leaf but in some species, is present on both sides and the leaves are said to be isobilateral.
So can hamsters eat leaves at all?
Its not good to feed them any leaves found in the wild, but it does depend on what type of plant they are from. In general because of this, it is inadvisable to feed them leaves of any kind. There are much better foods for them to eat.