Creature tokens you control have "{T}: Add one mana of any color."
Whenever one or more creature cards leave your graveyard, create a 0/1 green Plant creature token, then put a +1/+1 counter on each Plant you control.
If multiple creature cards leave your graveyard at the same time, Insidious Roots's last ability will trigger only once.
In the rare case where Insidious Roots is a creature token, it will grant itself the ability "{T}: Add one mana of any color."