This is defiantly one of those questions you got to ponder, I would say yes, as well as for imperio as science keeps proving plants are more complex than we ever thought.
The article says "when cast successfully on a living person or creature, the curse caused instantaneous and painless death", so that makes me think no- but tbh, I don't see why not. There's not really anything that contradicts the possibility that avada kedavra could kill plants
We've seen that it blasts apart inanimate objects it hits, so I'm sure that would get the job done. But if used on something like a big tree, I don't know. The spell severs the connection between the body and the soul, and I don't think plants have souls, so it's hard to say.
