Perhaps Mokuton stems from the power of the tree she got and was passed down the line to later pop up in the 1st.
And it seems to me that she either needs an army to invade her home plant or that she has been doing this shit a long time and plans to create another white zetsu army to replace the old one and let the world go back to normal before starting up another war and releasing that white zetsu army on it then turning those people into them and doing it again and again and again.
Watch Oro save the day. Perhaps this is why he wanted the body of all these KG holders. His research may have been done in attempt to become a reincarnation of her.
