How many leaves must cover the spine of the Lulav?
How the leaves of the Lulav grow: The Lulav contains a spine which is covered with leaves that grow at a distance of every four centimeters. Thus after the first leaf grows on the spine another leaf grows 4 centimeter above it and so on and so forth until the entire spine is covered with leaves. The leaves are on both sides of the spine, across from each other.
What is the law if only one side of the spine has leaves? The Lulav is invalid.
How many leaves must each side contain: If the Lulav has only one leaf growing on each side the Lulav is invalid. [This implies that if there are two leaves on each side it is valid]
The leaves must cover each other: The Lulav is only valid if the leaves cover each other as opposed to growing one under the other. This means if the bottom leaf does not reach the leaf above it, it is invalid. If however it reaches and slightly cover the leaf that is growing above it then it is valid.
 The reason for this is because it is no longer considered Hadar. [ibid]
 The reason: The reason for this is because the Lulav is not considered Hadar. [ibid]