I have noticed some people using arovos which turned completely black towards the end of Yom Tov. When discussing arovos, the halacha mentions the importance of the green color, since it shows that it is not dried out (which can be a problem if it's completely dry).
The black aravos has no green color which the halacha speaks of, but it's not dry at all -- the leaves look exactly as they did before. What halachic authorities discuss this, and is it permissible to use?