Edit this sentence

"He learned that although each tree is unique, they are connected with one root system."

I'm having a brain fart. My gut's telling me this is incorrect, with the each-they agreement. Am I right?

 

Here's a stab at it:

He learned that although each tree is unique, it shares a single root system with all the other trees.

 

I'm assuming that we are talking about a defined set of trees and not every tree in existence. If that's the case, use "each of the trees."

 

"He learned that the trees, though unique, share a root system."

 

Why wouldn't each tree be unique? Is that fact particularly important?

Each tree was connected through a single root system.

 

Each tree is unique but shares one root system, he learned.

 

Trees are stupid.

 

who will play the tree in the movie?

 

I didn't write this, but in the context, unique is important to the message of the piece.

 

Each tree shares a common root system.

Or

The trees share a single root system.

 

I thought they just spent their lives looking for wives.