Binding the Lulav

MISHNA: One may bind the lulav only with its own species; i.e., one of the four species taken with the lulav. This is the statement of Rabbi Yehuda. Rabbi Meir says: One may do so even with a string or with a cord. Rabbi Meir said: There was an incident involving the men of Jerusalem who would bind their lulavim with gold rings. The Sages said to him: They would bind it with its own species beneath the rings, which serve a merely decorative purpose and not a halakhic one.

במינו היו אוגדין אותו למטה – to fulfill the commandment of tying/binding, and this is for merely beauty, for Rabbi Yehuda according to his reasoning who said that a Lulav requires a bind, therefore, if he binds it with something not of its species, he would have five species (instead of four), and we hold that a Lulav does not require a band, therefore in this, the Halakha is according to Rabbi Meir.

MISHNAH: One ties the lulav only with its own kind, the words of Rebbi Jehudah. Rebbi Meïr says, even with a string. Rebbi Meïr said, it happened that the people of Jerusalem did tie their lulavim with golden jewels. They told him, under these they tied it with its own kind. Where did they move? At thank the Eternal beginning and end, and also at please, Eternal, please save, following the words of the House of Hillel. The House of Shammai say, also at please, Eternal, please give success. Rebbi Aqiba said, I was watching Rabban Gamliel and Rebbi Joshua, when all the people were shaking their lulavim but they moved them only at please, Eternal, please save.
If somebody returns from a trip where he had no lulav, when he enters his house he can take it at his table. If he did not take it in the morning he may take it in the afternoon since the entire day is qualified for the lulav.

The term "the frond of the date palm" employed by the Torah refers to the branches of a date palm as they sprout, before their leaves separate and spread out in various directions. Rather, they should appear as a scepter. This is called a lulav.

The Laws of Taking The Lulav and Its Blessings, 15 Seifim: 1. The mitzvah of the four species is for every individual to take one lulav, two willow branches, and three myrtle branches (and in a place where there is no valid myrtle, one non-trimmed branch is sufficient (Beit Yosef 646 quoting Orkhot Hayyim)). It is a mitzvah to bind them together with two bindings, one on top of the other, to make it nicer. One can use a different material [that is not one of the four species] to bind them. If the leaves under the binding fell out such that they interpose [between one of the species and binding] there is no concern (as one species does not [problematically] interpose itself. Therefore, one should be careful to remove the string that is often tied around the myrtle (Mahari"l)). If one did not bind it during the day [before Sukkot] or if the binding became undone, it is not possible to rebind it on Yom Tov with a real knot. Rather, one should merely loop around it. RAMA: There are those who suggest making the tie in a different way, wrapping around the three species, and then inserting the head of the wrapper into the loop (Tur), and this is the practice. The practice is to attach the myrtles slightly higher than the willows (Mahari"v). The myrtle and willow should be inserted deep enough into the lulav binding such that one can pick up all three in their hand while making the blessing (Mahari"l). There are those who suggest making three bindings on the lulav, and this is our practice (Mordechai ch. "Lulav haGazul").

If one wraps a cord of silver or gold around [the three species] as they are bound together, or wraps a [decorative] cloth around them and takes them, one fulfills his obligation. Taking the lulav through another medium is still considered to be taking it, provided [that medium] is one which gives honor and beauty [to the mitzvah, because]: "any entity which makes a substance more attractive is not considered to be a separation."
However, if one placed these species in a vase or a pot and took them, one has not fulfilled one's obligation.

If one wraps a cord of silver or gold around [the three species] as they are bound together, or wraps a [decorative] cloth around them and takes them, one fulfills his obligation. Taking the lulav through another medium is still considered to be taking it, provided [that medium] is one which gives honor and beauty [to the mitzvah, because]: "any entity which makes a substance more attractive is not considered to be a separation."
However, if one placed these species in a vase or a pot and took them, one has not fulfilled one's obligation.

If one binds the lulav together with the myrtle and the willow and separates between the lulav and the myrtle with a cloth or the like, it is considered to be a separation. If one separates between them with myrtle leaves, it is not considered to be a separation, because an entity does not separate between its own kind.
One may bind the together with a string, a cord, or with any substance one desires, since binding it together is not a required element of the mitzvah.