What's this? :3

the fern.

I don't know what it is, but I get them all the time from Mosser Lee LFS, and they're annoying as all heck. Nearly strangled several of my Neps. They're making a resurgence in my lowland shelf... I thought it'd be nice and give them a pot of their own, but they've made runners all over and are starting to spring up in a number of inconvenient places. Somebody like Tali might be able to give you a positive ID, or you might be able to find it yourself with a dichotomous key.
~Joe

A species of fern....with a massive rootsystem.

Hard to say what it is exactly but im guessing a common hardy fern like Athyrium filix-femina.
I got a ton of ferns like that that all look slightly different
Once it gets bigger it will be easier to identify.