Rules of kashruth for a lulav

What are the basic rules of kashruth for a lulav (a date palm branch, which is taken on Sukkoth as part of the commandment of taking the four species)?

Dear …!

The main features of a kosher lulav are as follows:

1. The length of the lulav has to be at least four handbreadths, which is 32 – 40 cm. (12.6 – 15.7 in.). This is the length of the “backbone” of the lulav, not including the leaves. 
2. The leaves of the lulav consist of two layers, which are connected along the whole length of the leaf. The layers of the middle leaf of the lulav have to be connected. It’s better that they be connected all the way to the top, but if they did separate a bit, the lulav is still kosher when the layers are connected along most of the length of the leaf.
3. The lulav has to be whole. If the tops of the top leaves had been cut off, the lulav is not kosher.
4. If the lulav is crooked to one of the sides or to the side of its leaves, then it’s not kosher. But if it’s leaning to the side of the branch, then it’s kosher.
5. If the leaves of the lulav are crooked and they lean downwards in a weird way, then the lulav is invalid.

Shulchan Oruch, section Orach Chaim, chapter 645