On Sukkot, Jews are commanded to use Arbat HaMinim, the four species, to "rejoice before God." The Four Species are: 1) Etrog (lemon-like citrus fruit) 2) Lulav (palm branch) 3) Hadas (myrtle branch) 4) Arava (willow branch). The three branches are bound together and referred to collectively as the lulav.