>Actually, I'm not categorically opposed to the notion, but I think you need to bring a lot to the table to explain why things without nervous systems feel pain.

Note that I didn't say they feel pain, just that they can feel what is done to them by the environment around them and respond appropriately.

The fact trees don't speak human plays a big role in us not understanding them, but they do clearly feel and express things whatever they may be.

>So is it immoral to cut grass?

Considering most of it is done for purely aesthetic purposes to satisfy human egos, arguably yes.

Note that whether it's moral or not is tangent to whether it can be done or not. We humans do plenty of immoral things without a care in the world.