Besides the sukkah which is a main feature of this joyous festival of Sukkot, there are the four types taken during morning prayer which are a prominent feature of this holiday.
The lulav (palm branch), citron (etrog), hadasssim (myrtle twigs) and aravot (willows branches) are all held together in both hands and waved in six directions during specific morning prayers during the holiday.
Why are we commanded to take these four types, and what might be the deeper derech eretz lessons of each separately and all of them together? Is a myrtle just a leaf? Is a citron just a lemon-looking fruit? You'll find there's a lot to say about this unusual collection.