What is stored in green vertex channel?

Hi, couple of questions if anyone knows.

1. What is stored in the green vertex channel?
2. What does leaf smoothing do, I am guessing some sort of normal manipulation?

By the way pretty sweet tree generator, the main couple two things it misses is manual leaf mesh editing, so that you can use those quirky random size atlases from megascans and some root generation.

there was something like a root creator before, i remember using it. Anyway, you can create "roots" with branch and branches, just put some branch at the bottom.
You can add your own objects in tree it and use them whatever you want, even as leaves and then you can use the settings of "mesh" tab to modify those objects