1) HALACHAH: HOW MANY LEAVES MUST REMAIN ON A DRY HADAS
OPINIONS: The Beraisa states that if most of the leaves of the Hadas branch have dried out, but "it still has three Badim of moist leaves" it is valid. Rav Chisda adds that the moist leaves must be at the top of each branch.
What does the Beraisa mean when it says that the Hadas must have "three Badim of moist leaves" left in order for the Hadas to be valid?
(a) RASHI explains that the Beraisa means that each of the three branches ("Badim") of Hadas must have three moist leaves (on top, according to Rav Chisda). However, the words, "It still has three branches of moist leaves" is unclear. What is "it" that still has three branches?
The RA'AVAD (cited by the ROSH) explains that "it" is the Lulav. The Beraisa is saying that "the Lulav still has three [Hadas] branches of moist leaves," which means that each of those three branches has three moist leaves on it.
The RITVA translates the word "Badim" differently. He explains that "Badim" means "Kanim," or "sets of leaves." His explanation of the Beraisa concurs, in practice, with Rashi's explanation: each Hadas must have at least three moist leaves left in order to be valid. When the Beraisa says "it still has three Badim of moist leaves," the word "it" refers to each of the three Hadas branches. The Beraisa is saying that if "the three branches of Hadas still contain three sets (trios) of moist leaves (one trio of leaves per branch)," then it is valid. That is, if each Hadas branch has a set of three moist leaves left on top, it is valid.
(b) The ROSH understands the Gemara differently. He explains, like the Ritva, that the word "Badim" refers to "Kanim" ("sets of leaves"). However, he says that the Beraisa refers to one branch of Hadas and not to three. The Beraisa is saying that if "it (one branch of Hadas) still contains three sets of moist leaves" anywhere on the branch, then it is valid.
According to the Rosh, however, what does Rav Chisda mean when he says that the three sets of leaves must be "at the top of each"? At the top of what must the three sets of leaves be? The Beraisa discusses only one branch, with one top (with space for only one set of three leaves)! How can all three sets of leaves be at the top of one branch?
The Rosh explains that Rav Chisda does not mean that the moist leaves must be at the top of the branch. Rather, he means that of the three sets of leaves on each branch, only one of the three leaves of each set must be moist, and he explains which leaf must be moist. The lowest leaf of the set, which usually is on top of (i.e. covers) the upper two leaves of the trio, must be moist, because it is the one that is most visible.
HALACHAH: The SHULCHAN ARUCH (OC 646:8) cites both opinions. The MISHNAH BERURAH (646:26) rules that the Halachah follows the first opinion, that each branch needs only three moist leaves left on top in order to be valid.

33b----------------------------------------33b

2) PICKING BERRIES OFF OF A HADAS BRANCH ON YOM TOV
QUESTION: Rebbi Eliezer b'Rebbi Shimon maintains that one may pick the berries off of a Hadas branch on Yom Tov, and the act is not considered "Tikun Kli" (the formation of a new, usable vessel), even though he makes the Hadas branch valid for use for the Mitzvah.
RASHI explains that one may pick the berries because his intention is not to fix the Kli, but to eat the berries. The Tikun Kli that results is a Davar she'Eino Miskaven, since he had no intention to make a usable Kli.
The Gemara asks that even though the act is a Davar she'Eino Miskaven, it is a Pesik Reishei -- even though he had no intention to make a usable Kli, his action definitely will result in the formation of a usable Kli. In the case of a Pesik Reishei, everyone agrees that the act is forbidden.
The Gemara answers that he has another valid Hadas branch, and thus he does not need the branch from which he removes the berries.
How does the Gemara's answer resolve the problem that his act is a Pesik Reishei? Even though he has another Hadas branch, when he picks the berries from the first one he turns it into a usable Hadas. His act is still a Pesik Reishei.