Cephalotus is peculiar in that

[Maybo]

Seedlings grow slowly into low-growing plants that spread through creeping, branching underground rhizomes. Cephalotus is peculiar in that it produces two main forms of leaves. （The Savage Garden: Cultivating Carnivorous Plants by Peter D'Amato)

Does the bolded “that” refer to “Seedlings…rhizomes”?

 

[kilroy65]

No. The phrase "in that" is similar to "because".

Cephalotus is peculiar because it produces two main forms of leaves.

 

[Tarheel]

@Maybo You could see it as a shortened form of the following sentence.

Cephalotus is peculiar in the sense that it produces two main types of leaves.