“Boughs of dense-leaved trees (anaf etz avot)” are myrtle branches whose leaves grow in groups of three, look like braids, and cover the stem, making them look like densely-leaved boughs. Each group of three leaves must sprout from the same node, that is, from the same height; if a hadas has one leaf higher or lower than the other two, it is referred to as a “wild hadas” and is invalid (Sukka 32b; SA 646:3). A healthy, vibrant hadas normally has three leaves sprouting from each node. One need not be too exacting; as long as the three leaves appear to the naked eye to sprout from the same height along the branch, they are threefold, even if one is in fact slightly higher than the others.
Three hadasim must be taken together with the lulav, and each must be at least 3 tefaḥim tall (c. 24 cm; under pressing circumstances, 19 cm). There is no limit on how long a hadas may be. Even if it is very long indeed, it is still kosher, but when bundling the hadasim and lulav together, one should make sure that the lulav extends at least a tefaḥ higher than the hadasim (SA 650:1-2; see 5:2 below).
Le-khathila, the threefold leaves must cover the full length of 3 tefaḥim, as some maintain that the hadas is invalid otherwise (Ge’onim). However, in practice, if the threefold leaves cover most of the 3 tefaḥim, the hadas is kosher, as this is the position of most poskim (Raavad; Rosh; SA 646:5). Even if the branch is 4 tefaḥim long or more, as long as the threefold leaves cover the majority of 3 tefaḥim, it is kosher. If there are at least 3 full tefaḥim of threefold leaves, even if the branch also has leaves that are not threefold, the hadas is kosher even for the most scrupulous (Baḥ; see BHL 646:9, end of s.v. “u-le’ikuva”).
The hadas produces small berries. They start out green and turn red and black. If the berries are green, the hadas is kosher. If they are red or black, and the number of berries exceeds the number of leaves across 3 tefaḥim, the hadas is invalid because it is of a spotted color. If one picks off the berries, it reverts to being kosher, but one may not remove the berries on Yom Tov, as it looks like he is fixing something (Sukka 33b; SA 646:2, 11).
Sometimes additional branches grow between the leaves. It is recommended to prune them (SHT 646:36).
If the top of a hadas is truncated, it is preferable to take a different one, as some maintain that such a hadas is invalid (Raavad; Ha-ma’or). If no other hadas is available, the branch should be cut in such a way that the leaves hide the truncated part, and then one may recite a berakha on it (SA 646:10; SHT ad loc. 32).
A hadas whose leaves have withered is still kosher. However, if it has become completely desiccated, to the point that it crumbles to the touch and lost all its greenness, it is invalid. If the hadas was soaked in water for a day and is no longer blanched and crumbly, we see it was not entirely desiccated, and it is kosher (SA 646:6-7; MB ad loc. 20).
. See above, n. 4. According to R. Naeh, hadasim must be 24 cm long. According to the updated measurements they must be 22.8 cm long, and 19 cm under pressing circumstances. (According to Ḥazon Ish, they must be 28.8 cm long.) The length is determined by measuring the branch, not including the leaves that extend beyond it. To fulfill the mitzva le-khatḥila, the branch should be measured from where the lowest leaves start growing. When calculating whether threefold leaves cover the majority, most of the length of the branch must be threefold, and le-khatḥila most of the nodes must be threefold. If initially there were three leaves at each node, and one leaf per node fell off, some say it is kosher (Ra’ah; Rabbeinu Yeruḥam; Ritva), and others disqualify it (Ran; Beit Yosef). According to many Aḥaronim, one may be lenient under pressing circumstances (SHT 646:21).