A forest floating in space may be a great and worthy idea, but it makes one heck of an ugly spaceship! From "Silent running", this is
Valley Forge.
And what better to strike fear into the hearts of the rebels than ... a flying dart? No, no! It's an Imperial Star Destroyer! It's a flying dart. It's an Imperial Star Destroyer! It's a ...
Or, indeed, a gigantic bug! That eats planets!
Or how about a huge ugly spider?
I'm sure there are more, and when I have a chance and feel like it I may run another selection. But that's enough ugliness for now. Let's finish with one truly beautiful spaceship, from one truly awful science-fiction series.