Humanity should respect animals.

[BrownEye]

But you can respect a plant and then kill it?

Are you sure it is "killed"? I mean it isn't dead until it is wilted.

And no it does not "scream" when you eat it or there would be many clairvoyants that describe this.

Although, it is possible for a clairvoyant to pick up a "scream" if you broadcast to it the intent to make it suffer.

This is talking lower plants, not trees.