Commentaire sur Soucca 3:3

נקטם ראשה פסולה – even this is not the Halakha.

A stolen or withered aravah is invalid.
One [take from an] asherah or from a condemned city is invalid.
One whose tip was broken off or whose leaves were detached, or a tzatzefah is invalid.
One that was shriveled or had lost some of its leaves, or one grown in a rain-watered soil, is valid.
This mishnah deals with the aravah, the willow.
Sections one and two: See mishnah one.
Section three: The first two details are again the same as in mishnah one. The third is unique to the aravah. The Torah specifies that an aravah that grows on a brook, or a wadi, is the type of aravah that should be used. According to the mishnah, this rules out the species of aravah called the “tzaftzefah”, which grows in the mountains and whose leaves are a different shape than the brook-aravah.
Section four: Of the four species, the aravah is the one that most easily dries out. Hence, the mishnah rules that if it is shriveled or lost some, but not most of its leaves, it is still valid.
The Torah states that the aravah is to be one that grows on a brook. The mishnah expands this to include an aravah that grows on a field watered by rain. The important thing is that the species of aravah is the same as that which grows on a brook. It is valid even if it is not actually found on the brook. This contrasts with the tzaftzefah, which is of a different species and does not look like a brook-aravah.

צפצפה – a kind of willow where its leaf is round,.

ושל בעל – where it grew in the field but not in a brook, it is valid. The words “willows of the brook” (Leviticus 23:40) were not said other than the fact that the Bible speaks in terms of words that are current.