How to get color from a Tree for Tree Instance?

Hi, does anyone know how to save the color of a material to be used in the TreeInstance method? I am wondering because generating a new TreeInstance requires a color or else the tree just turns out black or another pure solid color, and what I was hoping to do was save the color of the trees I can manually place and just use that color/material for the scripted trees.

An example of the code needed to set the color of the trees for TreeInstance() nextTree.color = Color.green;