The following is athought on the din of Hudus: for technical reasons I have to put it in the next post.

A Hudus (myrtle) needs to have 3 leaves in each row, because the Torah calls it "a braided branch" and with 3 leaves in a row gives it the braided look. The R'ah says that if one leave from each row fell off, leaving (no pun intended) 2 leaves in each row, it is Kosher, since we have a rule that for Halachic laws, most of something is considered like all of it. Hence most of the leaves that give it it's braided look are still attached, it's as all the leaves are attached. The Mishna B'rurah says one can rely on this if there is a pressing need.

The Steipler Z"l asks why then, once 2 leaves in a row is Kosher, is a Hudus Shoteh (lit. crazy myrtle. means that this myrtle does not have all 3 leaves in the same row, rather 2 in one row and 1 a little above or below it) not Kosher? Why don't you just pluck out the odd leaf and you have a myrtle with 2 remaining leaves?

The Steipler answers that a "crazy myrtle" is considered a different species than the regular myrtle (even though they both grow on the same bush, it similar to a caper bush that produces a few types of fruit, here too, the myrtle bush produces 2 types of myrtles). Thus , even if looks the same as a regular myrtle that one leaf fell off, it's not the right object to take, since it's a different species.

The Steipler in a footnote says that someone showed him a Rosh that says a crazy myrtle is the same species as a regular myrtle (therefore one is able to put crazy myrtles along with the regulars, and it wouldn't be adding on to the Mitzvah (Baal Tosef).

An objection I have, if someone had most of the myrtle with 3 in a row and the rest 2 in a row and one on top or bottom of it, it's Kosher. If you say it's one species, it's good, you have a myrtle with most of it has a braided look, so we consider as if all it is braided. But if you say it's 2 species, then you have only 2/3 of a myrtle and a 1/3 crazy
myrtle, so how can it be Kosher if you don't have a complete myrtle?

I would venture to answer, in my humble opinion, there are 2 ways to look at a "crazy myrtle". Is it a 3 leaf myrtle with the 3rd leaf in the wrong place, or do you look at it as a myrtle that has double as much rows as a regular one, and they alternate as rows of one leaf and 2. The whole question starts only if you say that you have rows of 3 but one is in the wrong place, thus the 2 leaves are most of the 3 leaves and should be Kosher. But if you see it as rows of 2 and 1, then you are not leftwith most of the row of 3, that would be considered as all of the 3. Rather you have a whole row of 2, and that will never make a row of 3.