A root is placed in the ground, or it can be the solution to something
Susanoo is in the sharingan roots just because only uchiha can use it
Idk what youre trying to get out of this thread
But what itachi means is that susanoo lies dormant/rooted
In his eyes until he activates tsukyomi and amaterasu
I guess this is about Madara using Susano'o without having his sharingan eyes inserted.
I've been saying you need both MS to unlock & awaken Susano'o for the first time
,but you , Madara, can use Susano'o afterwards if both eyes aren't inserted.
however maybe the Zetsu controlling Obito's body are emitting or transferring the ability over to Madara,
since Black Zetsu is Madara's will after all.