What do you do with the wither rose?

What is a wither rose? Besides a rare drop, I was wondering what it is useful for. Could it be used to make a wither skeleton farm? Just wondering. (BTW, I know how to get it. Please don’t answer with that).

Wither Roses can be made into black dye (Which is ludicrously impractical in the early game unless you are in an old style world with zero potential squid spawning zones, in which case you may be better off with a new world) and used for semi-automatic mob farms, as mentioned by Zyxilef. But, they can also be used for traps, and can be used to make suspicious stew that gives the Wither effect. Also, to answer your second question, you cannot use it to make a Wither Skeleton farm. Wither Skeletons are immune to the Wither effect. They can also just be a cool decoration, a trophy item, or a flex that you're rich enough to have them.