Hadassim (הדסים) are myrtle branches, one of the four species G‑d commands us to take on the Festival of Sukkot. The Torah describes them as “branches of a rope-like tree.”1 Rashi explains that this refers to the myrtle, whose leaves intertwine.2

Measurements

The Talmud3 teaches that a lulav must have at least three myrtle branches, and that they must each be at least three handsbreadths long.4

In order to fulfill the biblical requirement, a myrtle branch must have three leaves growing from each point on its stem. If only two leaves grow from each point in its stem, the myrtle cannot be used for the mitzvah of the Four Kinds.

There is no maximum number of myrtle branches to use with a lulav. As such, many have the custom to add in many more than the required three. Some put as many as 26 or even 36 myrtle branches.5

Meaning

The Midrash teaches that each of the four species represents a type of Jew.6 The myrtles, which smell pleasant but do not have any taste, represent those who have many good deeds, but do not study Torah. They, too, are bound together in unison with all other Jews.

Other Uses

Some use hadassim for the incense we smell at the Havdalah ceremony at the conclusion of Shabbat.7