Plants to aid your environment

Surly most plants are good for the environment! No plants means no pollinators, no pollinators, means no plants and no bigger beasties that feed on the plants and / or the pollinators and so on.
Obviously there’s a few exceptions to this rule. The one that springs to mind is rhododendron. Supports very little insect life & poisons the ground it grows in.

Have I over simplified things again? 

I have a rhododendron in the garden which is full of life!  It has briar roses growing through it and I have robins,sparrows and blackbirds either nesting or roosting in it. Whenever I walk past it it's like a scene from Hitchcock's THE BIRDS as they all fly out. For some reason the local cats don't bother the birds that are there either?
I know that in the wild the rhododendron is classed as a weed, but I wouldn't be without mine in the garden.

If you cut and store Rhododendron for a couple of years its a good wood for a log fire