Hey There!!
I Created This Roots Generator for all You Ruins, medieval, Fantasy etc. Architecture. and Trees as well it does have a demo procedural material. but better make your own matching with your environment. and I tested it Unreal Engine it works but I Used tri-planner Projection im too Lazy to Unwrap this.
Instructions and Important Notes::
Make sure your Object and The roots have same Location in viewport.
Select Object in Controls which are in Modifiers Panel.
and Move The Empty Object in Viewport.
When Duplicate more Roots make sure you also select the Empty Object as well. so, roots will have different empty for different Object.
You can put in Tree in Empty Slot and use it as Source Object as well in Controls.
Play with All the Controls to understand it, How much you can do with This.
there are 30+ Controls Parameter to give you be4st result as you want.
If your Object is BIG Increase Area. Move The Roots Position in Controls (named Transform Roots.) and Add more roots to your Object.
Like the Object please do a Review. it will help me a lot.